How often to wake a fed baby to eat?

My daughter will be 3 weeks old tomorrow. I've been waking her during the day every 2 hrs to eat and letting her set the nighttime feedings. She had gained back her birth weight by 1 week and is wetting / dirtying the right amount of diapers. My question is should I be waking her every 2 hours or should I try to stretch it out to every 3. She's doing quite well at night, with a 4 hr stretch and then a 3 hr one which I don't want to change if it means more night waking. So what did you do with your fed baby?