Hank S
En-Route
While it's certainly possible to slow down enough without flaps to extend the gear in my Cardinal, my SOP when flying an instrument approach is to add approach flaps for stability just before reaching the IAF. Then, gear down at the FAF, or when beginning my descent, if there is no FAF. I don't see any reason to alter that procedure.
Also, when descending into the vicinity of an airport VFR, I normally add flaps before the descent and then put the gear down when reaching pattern altitude.
This instrument procedure works well for me. But when VFR, I add flaps when slowing toward pattern speed, and drop gear abeam my intended point of landing to also start the descent. I descend from cruise altitude to pattern clean and power on, and let the speed build to make up for the slow climb.