
You should be able to spot the signs of the season before the bitch becomes capable of being mated.
Extra urine marking and enlarging of the prepubescent vulva are the first signs that a season is going to come soon, though with a few the first signs are a few spots of blood on the floor in the morning.
When I am waiting on a season every morning I dab the vulva with white tissue so I can spot the first day of bleeding. This would give you a day or two to arrange to board your boy, which is better than trying to keep them in the same house separated for around 4 weeks.
RE who to neuter there are more pro's than cons in eventually neutering the bitch, so that would be my choice assuming she has had time to physically and mentally mature.
If the season does not come until close to a year of age then 3 months after the first season starts would be the best time. Though is she comes in early at 6 - 8 months say, it may be better to wait until midway between her second and third season. the advantage to the latter is that it is easier to determine the midway point between seasons if there have already been at least two.