In Canada they won't do it below a certain age (low 20s) unless you take some sort of counciling course so that you understand the ramifications. They also advise those with newborns to wait until the baby is 9 months old (just in case it dies and you want another baby but have had a vasectomy so can't without a reversal - sorry to write that but it happens).
The doctor who did mine is famous in Ottawa known as the Vacetomy King, he is pretty funny too, you have to masturbate at least 3 times a week during the wait to test for sperm and he gave one of my friends a prescription to give to his wife with "blowjobs, 3 times weekly" written on it...