I think it depends on which symptoms you want to relieve as to how long it takes. The hot flushes disappeared within forty-eight hours when I first started patch HRT. What problems are you having with applying the patch? Femseven is notorious for coming unstuck and it is really important that you follow the directions to the letter - especially the part about holding it firmly in place with a warm palm for the right amount of time. It is important to get it to stick properly to the skin as the hormones are in the adhesive.
Good luck!
Taz