Let common sense be your guide. Honestly, everyone is different in their recovery and pain tolerance; I don't think there are any 'standard practices' when it comes to how long to wear a waist band. In fact, I really don't know what it is. I've had 2 c-sections. After the first, I was up in 24 hours and felt no pain; after the second I was up in 12 hours and felt no pain.
Do as much as you can to speed up your recovery. As aussigal, I was lifting my toddler a few days post-op and my doctor was fine with that as long as I was fine with it.
Obviously, do not push yourself and, if you feel pain, stop what you are doing immediately.