Try a A few practice lathers in your hand.
1) First soak your brush until it seams saturated, 2) then one shake or until water starts running out, 3) pushing on the brush enough to make good contact with soap, load for 30-45 seconds, 4) then start building lather in your hand.
The reason I say to do this is it actually lets you feel the qualities of the lather. Once you feel you have good lather, then put it on your face and see how it it feels and if it seams to dry, you can add more water. If it seams too wet, you know you need to increase your load time on the puck. This will work with cream also, you just have to adjust the amount of cream or add additional drops of water to your lather.
After doing this a few time you will have a pretty good idea of what you will need to do in the cup.
I thought I would share this as it has helped for a number of people I have suggested it to.