If you get your cha-cha heels and black leather jeans ready early Wednesday morning, you can get to 11 fashion events in this town in one day.

It's fashion blitz time in Washington, two-weeks of more than 50 substantial and numerous other fashion functions. On Wednesday, for example, you might catch the Mady Gerrad knits at Rizik's. Basile's collection from Milan at Magnin's, a Cacharel show at Bloomingdale's and talk to Stanley Blacker at Woodies. And that's just in the morning. There's also Soo Yung Lee at Saks Fifth Avenue, an Albert Capraro show at Hecht's and Garfinckel's party to celebrate the new Adolfo fragrance over dinner at La Serre.

That's the largest number of fashion events in a two-week period in recent memory - and more on one day than have been held during most weeks in the past.

Of course, it is fall, and stores are anxious to stake their fashion claims, and there are more stores in Washington than in any fall season before. As a result, the competition is stiffer.

"We do it for recognition as an entity in the market," said Magnin's President Norman Wechsler at the benefit for the Washington Home this week. "The purpose is not just the charity, but to get exposure in the Washington market."

"Being in a competitive market," says Vashti Mays, fashion director of Saks Fifth Avenue in Chevy Chase, "you can't just sit back. You have to keep the store's name floating around."

Even some stores which have never had designer shows got into the act. G Street Remnant Shop used a fashion show by designer Taba "to portray our fabrics and give the local city talent a chance," said Judah Greenzaid, owner of the fabric business who commandeered a separate floor of his building for the show of 20 garments in his fabrics.

But the front runner in the fashion marathon was Bloomingdale's, with 15 shows tied to a two-week French promotion. Most fashion events kick off in the New York store and filter to Washington, but these originated here, and New York got only a small, scaled-down share of the happenings.

According to Marvin Traub Bloomies chairman, the clincher for the promotion was the prodding (and financial boost) from a French apparel group and the commercial offices of the French embassy. They provided some of the money ("though we put in the lion's share," said Traub) and some of the organizational work to get the clothes and designers int the Washington stores.

"Washington is an international town with sophisticated people," said Claude Gitton, director of the French Apparel Center, which suggested the promotion to Bloomingdales almost a year ago. "Washington was an area we wanted to develop."

But is was, hardly a free ride for Bloomingdale's A condition of the collaboration was that the store include some brand-new talent in the promotion. So Bloomies came up with Claude and Chichi Barthelemy, Pan's ready-to-weardesigners.

Fashion events, while generally free to the invited guests or the public, add up to a sizable cost for the store.

Hecht's charges admission to their in-store fashion seminars in order to cover the cost of refreshments. But the store absorbs the cost of the models; and fashion director Ron Lichter wouldn't say just how much.

Saks Fifth Avenue divvied up the $25 ticket charge for the Chloe fashion show/Arena stage benefit: $20 to the theater, $5 for the store. Saks figures their expenses to be about $2,500 for invitations, models and rentals such as a runway, plus about $15 a head for food and liquor.

Magnin estimates their food costs alone on the Washington Home benefit at $30 a head for a sit-down dinner (from Ridgewell's). And that doesn't include the cost of 22 female and five male models at $110 each per event, including fitting & rehearsal time plus the loss in damaged merchandise that can never be sold.

(One model apparently put her heel through a pair of leather pants - admittedly not easy - and several others got their high heels caught in the escalator fashion show extravaganza. When it was all over, Magnin chalked up a loss on 40 pairs of shoes at an average price of $50, as well as some boots with a $175 price tag that now cannot be sold but will be used for other fashion shows put on by the store.)

So is it worth it? "In the long run, if you didn't feel you were having some kind of effect on sales, however immeasurable, I doubt we would do it," says James Schoff, Bloomingdale's president.

Clearly the clothes and the audiences have been frequently mismatched this season. The new broad-shouldered, retro-glamor clothes, military looks and black leather that most customers are seeing for the first time are considered quite shocking. And often the audience is not the sort to hop on to any new fashion.

Virginia Ogilvy, a docent at Hill wood and former textile and clothing specialist for the government who has been to three shows this week, says, "I know the clothes must shock for a fashion show, but why not a few pieces for John Q. Public."

Dorothy Vineburgh, an active colunteer in town, who also attended three shows, agrees: "No way will I wear those shoulder pads. I don't want to look like a peasant, but I want to find something elegant and comfortable."

Richard Krolick, staff director of a congressional committee, wasn't quite so kind. "It's like World War III," he said after one benefit this week. "They have got to be kidding." (Krolick says he is a fashion show regular because, "I'm a bachelor and have a black tie.")

(Lord & Taylor figures they've solved the audience problem for their Christian Aujard show for the Junior League next week. "We've picked a French designer who is in keeping with our favorite American classic look, and invited an audience that is sympathetic," says L & T Vice President Peggy Kaufman. "The League has always supported us. We wanted to do something for them. And they are synonymous with our kind of look.")

The cool reception at some shows rubbed off on the models who are having a banner week with unusually high salaries. "We were told to be very upbear and crazy for one of the shows," said Terri Jackson, a model who has worked several this week. "But I sometimes got horrible vibes from the audience." (Of all the shows she did, Jackson felt the audience liked best the Karl Lagerfeld clothes at Saks Fifth Avenue. Others thought the winner was the Emmanuelle Khanh show at Bloomies.

Some were not disturbed by the audience reaction. "To some extent it doesn't bother me," says model and N.I.H. secretary Charla O'Brien. "If I like the clothes I can show them well."

If the audiences didn't love all the clothes, the designers weren't always happy about the audiences, either. Thierry Mugler found that his audience at Bloomingdale's one evening included a group of kids shopping with their parents. He admonished one store executive: "You know, my clothes are not for children."

And it was clear that a totally unresponsive audience put Jean Charles de Castelbajac in a great huff, and he only reluctantly took a bow after one afternoon show.

If the customers aren't loving all the clothes and the shows aren't generating large sales, why are they doing it?

"I've learned a lot about the new fashions," says Virgina Ogilvy. "These shows are very educational."

And, to be sure, there is a reward for local organizations. The Textile Museum should gain about $10,000 from the Mary McFadden fashion benefit put on by Saks-Jandel next Monday night. The Opera Guild cleared about $9,000 from the Bloomies' party and The Washington Home close to $45,000 from that affair.

But there's no such thing as a free lunch - or even a glass of wine. Just how much is added to the cost of clothing by all this public relations blitz is not calculable, say the stores and the designers. But most admit it has to take its toll.

Meanwhile, where are the customers who buy the high-priced, avantgarde fashion clothes? A number of big spenders are currently in Morocco celebrating the wedding of the daughter of Ambassador and Mrs. Ali Bengelloun. They may have missed the blitz, but - judging from how the season has gone so far - there will be plenty of clothes on the racks when they get back.