If it's an assymetric runway approach then gear down at the FAF or GS intercept or equivalent place adjusted for distance & head/tailwind effects. If it's an assymetric circling approach then gear down when I commence descent to land after becoming visual. That could be on base, final, downwind ie wherever a normal descent profile intercepts my flight path. Flap also gets limited or no use until a landing descent is commenced. For light aircraft I prefer 'dive & drive' over 'constant descent' - I like the extra time to become visual, especially during circling approaches - but I've also needed to do lots of no-DME nor Radar supported non-precision approaches. Lots of them didn't have any ATS services on the ground either so Wx reporting was forecast only.
For all-engines approaches gear down at the FAF, GS intercept or equivalent and flap at least to approach setting.