What I've learned for seed starting:
heat is more important than light for the sprouting stage. So even a dark basement will do
once the plants are up you want to give them sun, but balanced with wind/movement so they don't get too leggy. I've envied my neighbors
greenhouse and she let me have some starts in there, but she keeps it closed up. So I've actually found that the starts I move outdoors in the sun and then indoors every night are much healthier then the ones in the light stuffy
greenhouse.
we have a south facing bathroom, and that bright warm wet environment has been great for getting the heat lovers (tomatoes, pepper, basil) sprouted and up.
allium family (onions, leeks) you can trim every so often to make them stout before transplanting
i usually wait to transplant at least until there's some true leaves (not just the beginning two)