I also took a fair bit of time when I rigged my mast to round out and smooth the cutout, so the sail feeds in easily and without wearing on the bolt rope.

I made the top edge quite square but got a round file up the track (so it funnels in) and into the corners of the slot to smooth it as much as I could. It means when the sail and mast are moving, the sail self centres fairly well, and lets you keep your momentum when hoisting. If wrap the halyard under the sole of you shoe and stomp on it at the base of the mast rather than trying to heave on it, it also leaves a hand free to feed the sail into the track.

To unhook, stomp and hold to hoist it clear of the hook, rotate the mast 120 degrees (I find one direction works better than the other) and release, and it should unhook.