Quote Originally Posted by Crake View Post
I have been trying to find the exact citation that states how the cooldown on abilities works, I remember it being in a super unintuitive rules section, and my table actually houseruled it, because it was actually just too much bookkeeping to keep track of WHEN you cast an ability on each day, so we just set it to recharge at sunrise, because it was easier, and we had a gentleman's agreement to not abuse the game.
The rule on how it's done is on page 6 of the DMG:

"Good players will always realize that you have ultimate authority over the game mechanics, even superseding something in a rulebook."

So your solution has backing from the written rules.