When's the right amount time to get married

My boyfriend and I have been dating for six months and everyone already says we need to get married, I feel that 12 to 18 months is an acceptable amount of time, my friend says six months is an acceptable amount of time, my boyfriend is in the Marines and he says to the appointments which is up to two years, what do you think it's an OK amount of time or doesn't really even matter? Before he actually been starting to talk about with the pros and cons with me about it