10 plants can be a lot to deal with, especially when half of that will fill the same space. Will your light cover corner to corner of this grow, if not you’ll have a few less than prize winning plants taking up space that end up producing - not much. More may not be better.
Feeding clones. Their root system takes off pretty fast once they get going. But it can take from 2 weeks to a month to get them to start rooting. So feeding them really depends on the root structure. Once they start growing and new growth is evident it is ready for a light feeding. Base it on the growth from there out. Don’t kill them with light starting off, DLI of about 15 is good until they take root, then gradually increase it until they are well established. Observe your clones closely, they need TLC. The humidity needs to stay high so they don’t wilt.
PH is a necessary must to keep correct. Sure it can and does drift. But checking and keeping it in check once a day will do wonders with young plants. Older plants can handle the drift a little better. Don’t think it doesn’t matter.