My tomato seeds just came in the mail even though I ordered them a couple weeks ago. I'm in zone 5B/6 and I was wondering if I start them tomorrow indoors, will they be late in the typical season?
Well.... yes and no. You will still get some tomatoes. But as a rough estimate you can figure about four months from planting a tomato seed to getting the first ripe tomato. So sometime in August. If your first fall frost comes early in October, you will have two months of tomatoes before they get shut down again.
When I lived in zone 6B, I planted tomato seeds indoors, somewhere around Valentine's Day. If it were me, I would plant some of the seeds, but I would also go buy a couple of well started tomato transplants from a nursery, so as to have tomatoes in the garden before August.