Almost immediately I would say. It only took a handful of pulls to get a good feel for it. I did buy the pressure gauge with it from the get go, I would definitely recommend that. Getting the whole process of preheating the brew chamber and getting everything ready in a streamlined manner takes a little practice though.
I use a TimeMore C3 manual grinder, and it does an OK job, especially for the price. I'm probably going to upgrade it (at some point) since it lacks some resolution in the grind settings.
I'm getting better and more consistent shots with this than my old semiautomatic brewer (a delonghi something, can't remember the model)