Hello,
Your study permit is valid even if you change the college/uni now or later once you land in Canada. Please check your conditional LOA and unconditional LOA, it will be mentioned that you need to apply for a college/uni which falls in SPP (student Partners Program) and in fact while applying for Visa also, it's mandate you apply for a college which falls in SPP. Both the colleges you mentioned are in SPP list. Hence, yes you can either initiate the process now or later, up to you. However, do read both conditional and unconditional LOA, they would have mentioned the conditions as well. Now, for the refund, as per the process, they refund the money to the originating account (if you paid this fee out of a loan account, money will be routed back to loan account). If you are going for September Intake, you have enough time, you can initiate the process now.
Hope it helps.
cheers!