Two or three weeks to sprout and get ready for transplant to individual pots. That gets me into the first week of January. January usually has numerous 60 degree days, so out in the direct sunlight on those days, growing under grow lights other days. Step up the pot size every three weeks or so. By March the plants are blooming. And by the time that they go in the ground in mid April the plants will be in two or three gallon pots and will have set their first batch of small fruit. Goal: in the ground by April 20th, first harvest of salad tomatoes by Mid to late May.
I won't start all of my tomatoes this early, but will start a few, and then will start a few more every two or three weeks through May or June. The latest starts will be the plants for the fall garden. This method provides a continuous supply of transplants of different ages/sizes and helps to ensure against some disaster.