Hey there,
speed is really besides the point. Everyone has its own pace so don't worry about that.
The best advice I can give you regarding that is don't stop then get back to it. That you'll definitely regret since your memory might not be as sharp as when you first started.
To get a good feel about how good are you in those chapters follow this
link. There are some really simple ones and some more difficult ones.
A good one which I would recommend saving for last would be the CD that came with the K & B book. Save them for last so you won't start memorizing the answers now and therefore invalidating your results on the mock up
test.
keep up the good work ;)