I think doing leg max the day before a leg workout would be fine, depending on how your legs feel and your goals.
If your goal is to grow as big muscles as you can, then don't (it would be like doing a Freestyle weight routine, the goal of which is to increase tone and strength without adding size). But if you just want to get firm legs without adding much if any size, it would actually be a good tactic (but one I'd only recommend for lower body, not upper body). Depending on how your legs feel, you would probably have to use lighter weights than usual for the lower body workout, but that would fit in with this goal.