I'm a morning person, but that doesn't mean morning is the best time of day for me to edit. Mornings are generally split into two types of time: writing on the train as I commute to work, and doing as much as possible as fast as possible on days I work from home. For me, the best time to edit is late afternoon. The mental pump is primed and running smoother than in the a.m. and not as intermittent as the p.m.
To do my best editing, it's important to go with my natural rhythm. In the afternoon, I'm less likely to put up with prose that isn't working, but not as likely to cut text that is working and just needs editing. It also helps the process to go from one environment to another. This can be as simple as going from my office to the family room, but changing my headspace recharges my mental batteries so that I can work more efficiently and see mistakes I would otherwise miss.
I'm blessed to have a fairly fixed schedule, which suites me because I work better with structure. Most people do, even if that structure varies. For editing purposes, it helps to find a rhythm that allows for these key aspects of creativity: a time to create, a time to pluck up what has been created and a time to rest from creating.
Everything is beautiful in its time. And, timing, as they say, is everything.
For a great prescriptive on finding your rhythm, see Turn, Turn, Turn this by the Byrds.