In Ontario you don't need a range membership to buy a restricted (I've bought a few over the years with no current range membership), so go ahead and buy a handgun ASAP before that window closes.
You will need a range membership to use the restricted, and may need it on PAL renewal in five years in your case (apparently they ask some of the time)... but a lot of ranges here have a waiting list, so might as well get that ball rolling as it might take some time.
If you do put your name on a waiting list somewhere, put that club's name down as pending when you purchase the restricted. So a good example is Range Burlington. I think I waited 1.5 years to get in. Put your name on their waiting list, buy a handgun and put Range Burlington (pending) when the seller asks for club. That worked for me; these days your mileage may vary.