Randy Gardner is a tomato breeder at North Carolina State University (he's bred many disease-resistant varieties)has also done many tests for early production. He says that over the years one simple rule has become dear: "If you want early tomatoes, you want plants grown in large containers"
"It's hard to do well by rushing the transplanting date much," says Gardner. "You are better off waiting for the normal tomato-planting time and setting out big plants with flowers on them. And big plants should be in big pots. A tall, flowering tomato with a small rootball will produce a few small, early tomatoes, then quit. There will be a gap until real production starts."
For lots of big and early tomatoes, Gardner recommends setting out an eight-week-old transplant in flower, in a 4" or 6" diameter pot. Start seedlings in 2" by 3" cells, and after four to five weeks, transplant them to larger containers and grow them on for another four weeks. If you want to start even earlier, then you should plan on moving up to even larger pots at eight weeks.
When the plants go outdoors, keep them well watered and actively growing. Go easy on fertilizer, though. "Tomatoes don't like or need high nitrogen, especially early in the season," says Gardner.