When to start feeding on demand?

dee12807

DD is just over 5 weeks old. I am still making sure she nuses at least every 3 to 4 hours during the day (she wakes generally only once between 9:30 pm and 6:00 am to nurse). How long do I have to push her day feelings?  I kind of feel like I should try letting her only eat on demand, but I'm fearful that if she eats less during the day that she wake more at night.  Any idea how long I should wait until she's fully 'on demand'?