Just follow the directions from Brooks. Don't make it complicated.
"Apply a small amount of Proofide to the finished top side of the leather, allowing it to permeate until dry. Polish off completely with a soft cloth to avoid getting any residual Proofide on your clothes. Also apply Proofide to the underside of the saddle. Leave this coating on to protect against dirt and moisture. Proofide may be used several times during the ‘breaking-in’ period and periodically thereafter. Do not overuse. :"
Note that you apply to the underside when you first install the seat, don't wipe off from the underside. After that, just apply a small amount to the top. I still have my original tin of Proofide from 2011. It goes a long way. The only reason I use more that most people, is that I occasionally apply it to my leather bar tape.