I've noticed this, but not got a specific time frame yet as I'm still on varying medication. But on the whole if I get to the point in the early evening and my eyelids are at their worst either through use or lack of medication or both, I'm unlikely to get them back that day without significant rest of a few hours. If I stay on top of things though, short rests of 10 mins to half an hour is sufficient. Like with any of these things it's always a balance. Harder to manage on busier days like today there has been lots of driving and computer use which always does my eye lids in.