Nickel size will take a while, since they normally have to get to 7 months or more before they will pair up and start spawning. However, this might not be a bad time to start getting ready if you really want to start breeding them. I got my first 4 angels in february, fully grown adults but did not have any pairs. Added 3 more and ended up with two pairs. The general recommendation is get 6 little ones and let them pair, you should get one or maybe two pairs. The thing is, adult angels need about 10g a piece, so you should have a nice size tank. And when they pair, you may even want to give them their own 20 gal
to do their thing. I got two pairs in a 30 gal
with a divider and when the fry went free-swimming I used a jar to keep them in the tank with the parents. They soon have to go to a grow-out tank. Good luck, breeding angels is where the fun is at.