You close the brakes before switching hands. No glider has a really
stable spoiler when cracked open and you can use the extra height to
extend your pattern while you put the gear down. A 40:1 ship can fly
over six miles from an 800-foot pattern altitude and has something like
5 minutes flying time available. From 500 feet make that 3+ minutes,
plenty of time to lower the gear.

If you first crack the brakes just before touching down (say at 50
feet) then you are screwed and deserve to break your glider. As I said
earlier, you'll need a few seconds to lower the gear so you'd better
have enough height.

I was trained to do all my pre-landing checks at pattern altitude,
cracking the brakes and visually checking both are open and to leave my
left hand on the spoiler until touchdown, which is the procedure I
still follow.

Mike