I've been doing 2 at a time without any problems although once I started reading through Aircraft General I made the decision to do that one on it's own just because of the amount to learn. Besides, the weather in Canada will provide some time to study Met & Nav so Im not too worried about it.
As said earlier, it's good to see other people in the same boat.
Alpha Male - Good luck with your Medical and Exams. You'll be fine!