The only time effects I've seen have been related to hydration and diet (like if I mow the lawn before a race and don't take in enough water). Other than that, I can have break-out performances at a 7am even or a 7pm event, or even a lunch-time power test.

Don't let BS like time of day get into your head. Your fitness is yours. You own it. You don't have fewer red blood cells when you wake up or something. Just ride.