Let other shoppers jockey for parking spaces, squeeze through crowded aisles and wait in long lines today, one of the busiest, craziest shopping days of the year. Tammy DiBlasi of Vienna was ahead of them all, and she didn't have to wait in the pre-dawn cold.

At 9:30 a.m. on Thanksgiving, she was on her laptop shopping for Christmas gifts. Around noon, she took a break to pop her 131/2-pound turkey in the oven, which hours later would feed her husband, three children and a dozen or so out-of-town relatives. Then she went right back to her laptop.

"I hate shopping; that's why I do it online," said DiBlasi, 40. "It's like a search-and-destroy mission. I know what I need, and I find the best price and then it just shows up at my house."

Online stores want more customers like her and are enticing them with discounts, free shipping and giveaway items.

This holiday season, shoppers are expected to spend nearly $20 billion on non-travel online purchases, up 24 percent from last year. While the Friday and Monday after Thanksgiving are typically bigger shopping days -- both online and in bricks-and-mortar stores -- some savvy shoppers checked their lists on Thanksgiving between bites of mashed potatoes and pumpkin pie.

"A lot of stores see the opportunity now where families are at home on Thanksgiving day and they've played football, watched TV and eaten turkey, and then there's no stores to go to, so they sit down at the computer and shop," said Matthew Moog, president and chief executive of Coolsavings.com and Freestylerewards.com, two online sites that offer coupons and cash-back deals. The typical Thanksgiving day online shopper, Moog said, is the person who is "really time-squeezed" and looking for a deal.

That's DiBlasi.

"I don't have time to go to the mall, find a parking space and browse through the stores. I have a full-time job and three kids who are active in church and school," said DiBlasi, who works 50 hours a week selling security software for Cisco Systems Inc. "If I do it online, I can do it anytime. It's painless. And it's much more convenient for me. I don't have to do it when my kids are awake."

On Thanksgiving, DiBlasi said, she checked three or four Web sites before finding a good deal on a pair of $30 iPod speakers. And in between watching the Macy's Thanksgiving Day Parade, cooking her meal, greeting her guests and taking in a little football, she looked online for a deal on a pair of $200 Bose headphones and a Lego chess set that typically goes for $50.

"I can't find it any cheaper, and my son loves Legos," said DiBlasi.

Even though she expects to spend about $1,500 shopping online this holiday season, DiBlasi said she is always looking to save a buck by getting free shipping or other deals. She also reads the fine print and makes sure things can be returned free of charge.

At ToysRUs.com, online shoppers could find the same deals that will be available on toys and games at the chain's 700-some stores on Friday, but they could get them a day early. Executives at the huge toy-store company said they typically see peaks in their Thanksgiving day online orders around midday.

"It's somewhere in between when people have finished watching the parade and they're waiting for the turkey to be done," said Melody Young, a vice president at the toy company's online division. Young said those who shop online on Thanksgiving are "looking for the convenience, versus the ones who go out to stores on Black Friday are making it a social event."

Some retailers, such as Barnesandnoble.com, are featuring discounts on DVDs and free keychains with purchases of toys and games to lure shoppers over these few days. Walmart.com said it offers more than 1 million products that are not available in its stores, such as an MP3 player for $100, silk pajamas for under $30 and women's cashmere sweaters for $35.

Retailers began preparing long ago for this onslaught of holiday online shoppers. Gap Inc., which owns Gap, Banana Republic and Old Navy, spent two years reworking its entire online system and debuted it in August in anticipation of the loads of shoppers who go online in earnest this time of year. The company installed new back-end software, redesigned the Web sites, and improved the way it manages inventories and tracks customers' purchasing habits.

"We allowed for it to start being used in August to make sure we had all the bugs worked out in time for the holiday season," said Alex Clark, a spokesman for Gap. As of late yesterday afternoon, he said it had been "totally smooth sailing."

Walmart.com said it prepared by ordering more backup servers, running practices of how long it takes shoppers to check out and simulating heavy online traffic. Thanksgiving is "a very, very big day for us online," said Raul Vazquez, vice president of marketing for Walmart.com.

Between bites of her tofu turkey, 30-year-old Erin Houchen sat on the floor of her Dupont Circle home checking out retailers' Web sites for gifts for the last few people on her list.

"I don't want to have to go to stores and fight with the crowds," said Houchen, who works as a Web designer at NASA and said she expects to spend about $1,000 this holiday season on gifts online. "I'd rather do it online. It's definitely about the ease."

Tammy DiBlasi shops online for Christmas and birthday presents during her spare moments on Thanksgiving.

A shopper uses a comparison Web site to research buying a digital camera.