It is an individual cat thing really - some males don't ever spray, but a lot of them do begin as they are becoming sexually mature. I have heard that it MAY prohibit the behavior if you have them neutered BEFORE they become sexually mature. Your vet is your best counsel, but you should wait until both testicles have descended, usually by around 4-5 months.
As a side note, my stud, Tonka began spraying when my queen, Lexus had her first estrus - and boy did he hose this house!!! He was about 9 months old at the time.
Hope this helps,
Old Style Siamese Cattery