Hi, first time posting.

My office decided to train us up on the latest products that are out there and therefore I was placed on a course which introduced the 70-646 exam Windows 2008 Server Administrator. This is my first time learning about Windows Servers, although I have worked on them over the last few years.
Cutting a long story short, for the last few weeks I've been studying the material and have some grasp of the concepts, but feel I need some more time I booked an exam but have rescheduled it to January due to an increase in workload.
Now that I have more time, I'm in two minds whether it might be better to switch to doing 640 and/or 642 before doing 646, would this be better?
Or should I stay the course and solidify my knowledge in 646 and complete it in January?
Thanks for your replies in advance.