nothing to lose by trying them. if they haven't grown in 3 weeks the chances are they wont grow.
They probably wont be 100% identical to the ones you saved them from but they will still be nicely edible.

As SBG says, nothing to lose, and tom seeds sometimes start sprouting while inside the parent tomato so I don't think there is some kind of natural growth inhibitor that has to vanish first

I grow yellow cherry toms from self saved seeds, Balcony variety and they seem to come true.

Thanks for replying Seaburngirl & Grandad I’ll keep a check for few weeks ,if not will replant other seeds

If the tomato was completely ripe to the point where is almost rotted, it should be OK. The seeds are encased in a small jelly-sack which is an anti-germination agent. No telling what you will get when they do germinate. I'd spring for a packet just for backup.