Canadian mamas when do we apply to maternity leave?

To my fellow Canadian moms, when do we apply for maternity leave? I am due June 8th, but I am planning for my last day of work to be May 17th because I work a fast paced job that involves an hour of travel to get to work. It is already getting to be too much!

Do I apply to maternity leave on my last day of work? I am just curious as to when I can expect to start receiving maternity leave in terms of budgeting until then! Currently been on hold with service Canada for 20 minutes, so figured I’d ask here too lol!

Thanks in advance!