It truly depends on the approach and a number of other factors, an frankly on how the pilots want to fly the approach. I've done the same flights weekly for a few months and observed very different patterns - sometimes we'd do a big circle (not a holding pattern - the wind dictated doing a 270 before landing) with the gear down for even up to 10 mins flying very slowly, and sometimes the gear was down only on what appeared to be the short final.
The first "gearlike" sound before landing is usually the flaps extending. Depending on the type and where you seat, the sound may not be easily distinguishable from the gear extending. The latter is usually followed by a loud thud as the gear locks, but the loudness thereof that also depends on the type and where you sit.