Zone 5 is it? I think you will be fine, Most of the seeds I plant say 4-6 weeks prior to planting out, so you should probably be right in the correct timeframe there. I am assuming you plant out in late may?

No problem at all IMO. You should still be able to plant out at your normal time. They just may be a bit smaller transplants but they will quickly catch up once transplanted. The worst that could happen is that you first fruit set may be a little delayed depending on the weather.

Dave

IMO it's not "too late" for tomatoes from seed until you get into May/June! You may end up planting out smaller plants, but that's no big deal. Better than nothing, right?

I have direct seeded tomatoes with success in early June in zone 7. I usually set out plants about May 1st, so any head start you can give inside should be fine.

I am in zone 6 and haven't started my mater seeds yet. Last year I did start in March and they got a bit bigger than I wanted before I could plant them, so I am waiting until this weekend to start. One thing I do is presprout the seeds. They germinate very quickly and you can save time by doing that. I put the seeds on a damp paper towel inside a plastic baggie. Maters sprout within a couple days or so.
Keski