I found this article a while back:
http://www.ottawasun.com/2011/05/27/understanding-condo-registration which has some helpful info.
This is what it says about occupancy fee:
When you move in, you have to pay an occupancy fee to the developer until such time as the condominium
corporation is officially registered. This fee is determined by the interest portion of the balance owing on the purchase price (usually payable on the registration date) based on a one-year mortgage rate of the Bank of Canada, plus the estimated maintenance fees for the suite, plus its portion of the estimated real estate taxes.