Is there a window in a Womans cycle that makes hair removal more comfortable as far as pain goes? Should a woman consider this window when making advanced appointments for the procedure? Obiously, I know that one should not go while on ones period for this would be uncomfortabe for both the practitioner and the patient but what time during the cycle is best?
It depends on what part of the body is being treated…
But if you use a numbing cream then you can get treated at anytime of the month and you won’t feel a thing 
It all depends one the person’s personal chemistry and internal balance. A healthy woman with no hormonal imbalances would have the potential to do work all month long. Those suffering from voluntary imbalances, (use of birth control pills, artificial sweeteners, caffeine, Nicotine) would have more potential problems.
Getting the body’s hydration levels, electrolytes and B-vitamins on track would help out a whole lot.
But to answer your question more directly, I have had people who have required avoiding that time of the month, and others who actually did better having their treatments scheduled for that time of the month exclusively.
Menses is not a problem for most. If one is told that it could be more uncomfortable, then the woman starts to believe that it is. Some use it as an excuse for increased sensation, but they still do fine. Complaints happen even when one is mid cycle, so who really knows. If one is that uncomfortable during her period, then schedule sessions accordingly.