please note this can with medicals. have nt seen anyone get POF request after medicals so far.. u have to show POF at the time of landing in canada as well.
Yes they can check POF in your bank at any time before issuing visa. POF is the most important part, because they don't want you to burden on government funds after reaching there. So make sure that you must have required amount of funds till the visa stamp on your passport.