Part of me tells that 8am is fine, just get it done with that morning, first thing in the day, rather than finicking around and getting confused on last minute concepts

Of course 8am means I should be there by at least 730am, which means I need to be up by 5am.. OMG.. that is something...
Amazingly the most common timeslot available is 8am, I guess not many takers there! I cant find anything beyond 8am.. It is very hard unless it is a weekday.. and months out..
akaydee
mainhoon,
I think the best time differs from person to person. Having said that I think you should check when you feel the most alert. Try and find an alternative time slot. There might be one that might open up if somebody decides to defer his/her test.
In general, most people have a dip in concentration levels between 2:30pm - 3:30pm. It's that time of the day when when you need a cup of coffee or some extra sugar in your body. So perhaps that's something you should keep in mind.