I think that is bad idea to take it only when awake.
I recommend every 3h in the first 6-8 months. This depends on your recovery. I chelated 14 and still can handle the 4 hour clock. My mercury burden is huge and my body is weak and. If your body is stronger than mine and feel good with 4h taking - do it. But is strongly advice you to take antioxidants + 3 hour dosing ala Original Cutler Protocol