I've had my Monstera deliciosa for about eight months now, and I'm still waiting for those signature fenestrations to show up

I've had my Monstera deliciosa for about eight months now, and I'm still waiting for those signature fenestrations to show up. I know they're supposed to appear as the plant matures, but mine is putting out new leaves that are completely whole. I'm in a cold climate, so I'm wondering if that's slowing things down, or if I'm just being impatient. Does anyone else's take forever to fenestrate, or am I doing something wrong with light levels?