Canada Visitor Visa & Extension
A visitor visa may be for single entry or multiple entry use. Single entry visas may be issued up to six months before the expected date of travel.
Visitors are not allowed to stay in Canada more than their validity visa period. But visitors may apply for extension to stay longer. If you decide to stay longer, you must apply for your visa extension 30 days before your Temporary Resident Visa expires. If you stay longer than the period you are allowed, you may lose your temporary resident status and you could be asked to leave Canada.