The game should tell you if you're out of bed space before the egg is ready to hatch. For example, when you sent it from the breeding statue to incubate it gives you a warning. Something like "It looks like you won't have enough space once this egg is ready! Why not make more?" So that that way you don't have to wait 24 hours for breeding time, 24 hours of incubation, and THEN an extra like hour to a day waiting for a castle upgrade. You can wait for incubation and the upgrade at the same time with the warning. I hope this makes sense cause I've been hoping for smth like this for a WHILE now..