When can i stop waking baby to breastfeed?

Morgan
My son will be 6 weeks on wednesday & is exclusively breastfed. In the first weeks i remember the hospital & the docter telling me to wake him every 2-3 hours to breastfeed. He has been gaining weight very well & having plenty of poops & pee's .
My question is as what age do you stop waking them every 2-3 hours to feed? 
Like i said he is almost 6 weeks, we still usually wake him every 2-3 hours during the day, but for the 1st time last  night he slept 5 hours inbetween a feeding & i felt so guilty. People say they will wake to feed when they need it.. But will he stop gaining his weight well if i stop waking him every 2-3 hours? & just let him feed on demand ? 
Thanks