It is NEVER too late!
I have heard so many people lately worried that they have missed the season. "It's too late for...(fill in this blank.)" It's not. It's not too late to go back to college, start saving for retirement or to get in shape either. You may not have the first tomato on the block, but it's no too late!
Gardening should be fun and rewarding, not a race. Truth is, if you get
those tomato plants started in December and transplanted in February
and spend twice what they would cost you to buy protecting them with
every imaginable contraption to stave off the cold, you wouldn't be that
far ahead! Unless you have buried a soil heater in your garden, they
are not going to grow much when it is cold.
At my garden center the gold standard of success was (and is) basil. We would struggle with it all winter to have some in stock. One of the die-hard rules for our system was to write the planting or most recent transplant date on the back of the tag when they are handled. We would plant it in December and work hard to get some size on it by February. Basil planted in March took three weeks from seed to finish in the hot greenhouse. Don't expect this at home unless you have a greenhouse and keep it hot. My point is: early doesn't give you much of an edge. When the sun gets at the right angle and the heat comes, things just click.
Furthermore, IT IS ALWAYS TIME TO PLANT SOMETHING. Georgia Organics has a neat calendar that will help if you want to know which plants will thrive if planted now:
I love this chart! I have it laminated in the kitchen of the farmhouse!
Keep in mind, if we have a cold Winter and Spring, the cold weather section would stretch out farther. If we skip Spring and jump straight to Summer, the hot weather section will start a little earlier. That is the gambling game of Spring that makes some gardeners and farmers feel inadequate.
Let. It. Go.
On big commercial farms they do plant things before the frost date and try to cover them when they are wrong. But they don't linger over mistakes. They buy new plants and replant if the stuff gets killed. They have to. You need to do the same.
And remember: if the greenhouse gardener is ahead of you on tomatoes, it doesn't matter. When the soil temperature gets over 65, the tomatoes are all going to grow!