We do the same as Alejandra. 9/10 he's fine until his next feed and just let's out a bigger burp during that one
I do a very light burp over my shoulder whilst she is asleep and that's it. She always falls asleep at night whilst feeding.. but then my baby is breastfed so doesn't take so much air. If they're gassy, they'll wake anyway.
What we do, we try for around 20 mins, if it doesn't happen, we put her to sleep. If she actually has a burp she will eventually wake up asking for it. Not sure if this is right though