So many! astros are my favorite genera of cacti. they are all going to be so cute!
I have a bunch of astro seedling growing from home made seeds (ornatum X myriostigma? They were all blooming at the same time) only about 10 have sprouted so far. I have them in some little container thing to keep the humidity up, and they get a few hours full early morning sun. They seem to be doing great.

Yours look great, so i wouldnt change anything. Hopefully they all march on out and take over the world!