average is probably right around 11 dpo. it can be anytime between 6 and 18 dpo, but most are in that 10 - 12 range, if you are sure of your dates. (if you belong to ff, they have lots of stats, and i would look it up for you but my vip just expired. i do know they say if no af by 18 dpo and bfn, ask your health care provider what is going on.) re: how long it takes, there supposedly is about a 25-30% chance of conception in a perfect cycle wtih well timed intercourse. i think it's safe to say 4 mths is not unusual at all. some get lucky first month, others it takes a year or more. after a year, if you are under 35, you should talk to a doc about it. if you chart and know everything is good with your cycle, you might talk to a doc after 6 mths. if you've got an easy going doc, they will start looking at the easy stuff anytime you ask. some of them make you wait a year.
do you chart?