When one asks how long will it take for any area, please keep in mind that there are many variables.
Specifically, for your legs, the question I ask back is how many hair follicles do you have? Of course, you will not know. Length of time depends on whether you have scant density of hair or copious amounts of hair, how efficiently and fast your practitioner can tackle a large area of hair. Many can do the size of your palm clearance and others only get a coin size area in one hour.
I am impressed with the results of lasing leg hair first, if you have dark, coarse hair and then finishing up with electrolysis to grab the rest of the hair that laser could not affect. The lower legs respond well, usually, but the thighs can be be more problematic. There seems to be a higher ratio of “roots” that are white as opposed to black. We need BLACK roots for laser to be effective.
Using both modalities is really a good choice to speed this along, especially if you are really hairy.