Inauguration fans, it's time. The envelopes are in the mail, the souvenirs rolling from the assembly lines. Commemorative invitations that get you nothing, actual invitations that allow you to get something if you pay for it, order forms and more order forms, souvenir silver medallions and porcelain eagles, official license plates -- the inaugural flood is on.

Yesterday, President Reagan received the first inaugural license plate with the inaugural seal. His is number 1.Vice President Bush got number 2, and Transportation Secretary Elizabeth Dole a plate emblazoned with DOT1.

The rest of us will have to wait for the mail to arrive. The first mailing went out this week: oversized cream-colored envelopes packed with a variety of goodies. But not all of the envelopes come with all of the options. Three hundred fifty thousand people will receive the commemorative invitation, requesting the "honor of your presence" at the inaugural, and the accompanying note explaining, "This invitation commemorates the official swearing-in on Sunday. It does not constitute admission to any of the inaugural events."

There are, for more than 50,000, invitations to the balls, with tickets available at $125 a person and boxes accommodating eight people for $2,500. Seats for the inaugural parade go for $12.50, $75 and $100. American Express, MasterCard and Visa are accepted.

And if memories just aren't enough, consider the preliminary souvenir brochure. The "Porcelain Soaring Eagle" by Boehm Studios -- $950. Cuff links and tie-bar set with the official inaugural medallion portrait of Reagan and Bush -- $25. A numbered license plate, authorized for use on your car from Dec. 15 to March 15 -- $30. A personalized plate (up to six characters) -- $50.

"There's one theme that runs through all our products and really all the inaugural," said inaugural committee marketing director Doug Blaser yesterday. "It's 'We the People, an American Celebration.' "

Blaser is now studying sweat-shirt and poster designs based on the theme and other products the committee will license and offer for sale.

"Everyone loves sweat shirts and posters -- all ages," he said.

"I kind of tried to typify the kind of person who would be interested in the products," said Blaser, a marketing consultant from Denver who served as deputy manager of the Republican convention before joining the inaugural committee. "There are the collectors and there are the history buffs. There are those who are President Reagan and Vice President Bush supporters and fans of the president, and also the presidency. And there are pragmatic purchases for those interested in buying gifts."

The pragmatic line is topped by the license plate, which Blaser said is a popular Christmas present.

But this is all only the beginning. By next week there'll be more mementos, more information, more invitations, more envelopes. Keep your eye on your mailbox.