I didn't really consciously hour build as such, as before I decided to pursue the CPL/IR etc I'd just been racking up lots of "useless" (but great fun) hours flying lazy aeros.
So the CPL was actually a bit of a shock to the system!
My advice would be spend less time on the GH and more on nav. On the GH it's going to be better to have an instructor tell you if you're doing it right rather than you reinforce what might be bad habits on your own with noone telling you otherwise. There's plenty of time on the course to sort all that out.
On the nav side, try and fly vaguely test profile type routes, that is, a 50nm or so route to a small-ish town, followed by a diversion. Ok, it's difficult to "surprise" yourself, but I suppose it's feasible, that after finding your original destination, pick another place to find and start getting used to planning the diversion on the hoof, that is drift, groundspeed, eta, check the route for airspace, danger areas, etc. Try and fly through at least a MATZ or some perhaps some class D, and be disciplined about making sure you're always speaking to someone for a FIS wherever possible. Get very slick at RT! It really needs to be second nature.
Hope this helps, SS