Yes - it is, I've just done a test at 0830hrs and thought it would be heaving but it wasn't.
In some ways it is a better time of day to do your test because you have to go slower. in queues. You can only go when it is safe and clear to go. Most drivers co-operate so I'm sure there will be many who go out of their way to help you.
The next day it could be you driving doing a school run? So you know how to deal with all the various junctions, traffic lights etc. Make yourself use your mirrors all the time, have eyes in the back of your head BUT take it slowly and you will be just fine.
Slow and controlled is the way to go. Leave good gaps but go with the flow of traffic.
Good luck and I hope it all goes well. If not climb back on and try again, use the test as a learning experience.