Impotence is really the wrong term to use. It's the refractory period between male orgasms. As said here, it can be fast when you're between 15 and 30. As you age it will reach 24 hours then 48 hours and eventually much longer. So relax, 15 minutes is hardly anything at all.
Well, I am 38 and there are times when it doesn't go down and I have an orgasm 10 minutes later. Then there are days when it goes down and just doesn't want to come back up, no matter how long has passed. Just be happy if it does take 15-30 minutes. Some guys just *** and then that's it for the day.
First of all, tell me how old are you ?
when you are young between (16 to 22), u r on highly hormonal and you could be ready for the next round of sex with in 10 minutes. but with the passage of time and as much as u practice more sex, ur erection duration is decreased. it can go down from 10 minutes to 30 min and may be some time to one hour.
some men put their clothes on and physiologically when they are dressed they get erection quick enough. so not to worry, first never take stress in while u r having sex or any pressure. sex is for pleasure and when u r tense you can't perform.
when i was 20 years of age, i could have sex 5 times while my penis was inside my gf. so 5 times in a row. but now i am 31 and i need at least 30 mins before the next round.