You can evolve Nidorino the moment you get a Moon Stone, preferably before Level 23.
Nidorino gets Focus Energy at Level 23, Fury Attack at 32, Horn Drill at 41 and Double Kick at 50, if you don't evolve it.
Out of these moves, none are really helpful—Focus Energy isn't worth the go when in-game is all about all-attacking and it lowers critical hit chance. Fury Attack isn't better than Thrash, Horn Drill relies on luck while grinding to Level 50 for Double Kick is totally unworthy of effort.
However, if you evolve it before Lvl 23, it will get to learn Thrash. Thrash is an incredibly good move with Base 120 Power, and the confusion won't matter a lot since you can switch-out freely.
Therefore, I suggest evolving Nidorino before Level 23 so that it gets Thrash as Nidoking.
Hope this helps!