The POF may be asked at any point of time during processing your application. The best POF is to get a certificate of savings from bank. The certificate must mention your name, address, account number, account opening date and current balance. The current balance is good to be in CAD, if no than you may attach an excel sheet by converting the currency to CAD at that day currency conversion rate. Bank can easily give POF in CAD if you ask for the same in written and confirm the purpose of POF. They may initially say no but you can argue about this and put your point strongly. They will issue the certificate in their currency selling rate which will be slightly higher than the market rate and your CAD amount will be a little less than your calculations. But believe me this will be the actual value as when moving to canada in any case you are gong to buy the currency from your bank on their selling rates.