4 months sleep routines

ok so my son is 4 month old has always been a great sleeper his current bedtime is anywhere from 9 to 9:30 and wakes up at 8:30 since I can remember although everyone else seems to put their child down at 7 and they woke up at 7 a.m. but I don't know if I can do that we have tried to put him down at 7 and he will literally cry and cry and till 9:30 or 9:40 and just pass out from exhaustion do I have to change your bed time to sleep from 7 till 7 he does get about 13 hours sleep a day I just don't know if I'm doing it wrong because everything I read says I'm doing it wrong... help? sorry for the crap grammer actually using this speech to text