[Canada] Change of use of personal vehicle and DPA consequences

Hey folks,

I'm preparing my return and since my firm reimburses me gas and all at that .52 rate, it used not to make much sense to deduct my vehicle costs while still going to college for most of the year.

In 2015 however, it makes financial sense from the scenarios I made. However, I've been using my vehicle since I started for the firm. If I want to start raking in that CCA, am I still hit by the 50% rule even though I used the car in the past? Does the change of use occur in the year I decide to claim, or in the year I start actually using the vehicle for the job?

I'm trying to find a way to solve that if possible, since otherwise at 50% it's not quite worth the effort and trouble, unless I do it in the prospect of being able to really cash in on that next year.

Thanks!