I am Canadian PR and I am planning to bring my mom and dad to Canada under visitor visa. I am not sure when they will come but I need to get the visa done so when they are ready they just have to buy a ticket. Question I have is I am planning to put the dates as 2023-Sep-01 to 2023-Sep-21. If i put such dates do they really need to come during that time? Will it be a problem if they come around 2024 April ? Thank you