Does one apply Carac at night, or in the morning?

I believe it is a time release medication, and night time use might limit its effectiveness if I wash it off in the morning.

I have been putting it on in the morning for 3 weeks, and now my refill says I should put it on at night.

I can always call the dermatologist on Monday, I suppose.

Thanks.

This is medication for pre-cancerous keretosis!!