At the tail end of the germination process. leave the seedlings in there for an extra week or 3, so that they are *physically* big enough to survive in the pots or the garden beds. I transplanted a bit early and the rain physically smashed them into smithereens.... *sigh*
Its a pain, but you have to really look after them after the transplant process for a few weeks making sure that they are fully protected from the elements for a while until they are big enough to go into the outside world on their own, go to school, get a job and start a family... bless their little cotton socks ... ;)