I use a similar procedure but I move them to light as soon as any of the seedlings sprout. Once one sprouts, they pretty much all sprout, and there's no sense in letting them get leggy while they search for light. :)

<I've always been unsure though as to when is the best time to remove the covers>

Yes as soon as the seedlings emerge. And don't wait for all to emerge either as that is too long and you risk damping off. The plastic domes/covers aren't really needed for germination anyway and aren't used by professionals. They often cause more problems then they solve so remove them ASAP.

As to lights, if not germinating under the lights (as some do) then move them to the lights ASAP.

Cooler temps - 60-65 is a good growing-on temp once germinated.

Dave

My sowed pots are set under lights immediately (unless the seeds need darkness). I don't use domes, but plastic wrap my 4" containers. When I see germination, I may wait a day or two to get more plants up, but that is about as long as I wait. I have never had an issue with damping off doing it in this way. BUT, I also only water once after sowing the seeds and putting the plastic on, and the seedlings won't see water for some time!

You are right Dave pros don't use the plastic humidity lids. I've watched them at my favorite greenhouse. They either put them on a conveyer belt under a mister or they put them in a propagating chamber. Since we home gardeners have neither of those machines we use the plastic domes to retain the moisture needed for plants to germinate.

I find I get better germination with the lids. I leave my humidity lids on until most have germinated. It is only a day or 2 from the first sprout until most of them sprout. An extra day or 2 is not going to promote damp off if you don't make your soil too wet to begin with. This works for me but there are as many ways of doing things as there are gardeners so experiment and find the way that works best for you.