When do you castrate your wethers?

[northcoast]

I've got two bucklings from a set of quads, one of which will get the pinch from the Ritchey Nipper right away. Cieran, the other brother, I would like to breed with one of my Saannen / Kiko does before he meets up with Ritchey. Has anyone else done this and did you have any issues? What should I look out for other than typical buck behavior?

Side note: I will wait the full cycle to see if she comes into heat again just to make sure January is prego.