Upping dose, when do you see improvement?

My daughter has been on Prevacid solutabs since she was 2 months old. Her dose was 1/2 tab twice a day (15 mg total). Her symptoms improved while on this dose, but her sleeping habits did not. Fast forward to now. She’s 18 months and was still on the same dose. Still sleeping like a newborn (waking up every 2 hours wanting to nurse). I found this website and after reading that she was probably undermedicated (marci-kids dosing), I convinced my pediatrician to up her dose, which he did to 15 mgs twice a day (30 mgs total). He was not happy about increasing her dose, saying he thought her waking up during the night was out of habit and that I need to let her CIO. I really don’t want to do the CIO method because I’m unsure whether she’s in pain from reflux or not.

Anyway, my question is: when upping the dosage, when do you expect to see improvement, if there is going to be any? Does it take the full 2 weeks like when they’re first put on a PPI? She’s been on this new dose for 5 days now and it *seems* like her sleeping has improved somewhat (she’s sleeping in longer stretches, but by no means sleeping through the night). She’s decided she’s going to start teething again at this time too, so I can add this in to the mix of is it reflux, teething or just habit. Ugh.