Clean dry skin is best, so just after your shower is great.

But there is no hard rule  - You can apply right after your evening or morning shower or you might decide if you shower in the evening that you don't need your Woohoo at night and apply in the morning!  Or you could have a very energetic job or lifestyle and need a couple of showers and reapply after those.  Woohoo can fit into your routine however you like :-)