The books and sports psychology info I've read say any change in a given learned motion require 3000 to 5000 repetitions to become ingrained. Now, I believe that they were implying changes to an already accomplished athlete. So, maybe if you change your grip a bit, or your stance maybe, but for a brand new player this would not apply.
In short they suggest changing, or working on ONLY 1 thing at a time, and giving it enough time to become 2nd nature so to speak.
good question!