Do dig it out and pot it - next April. It's now full summer as far as the tree is concerned and not a good time to dig... the best time is just before buds open - have filled out but not yet leafed. Are you sure though that you want a tree with such large leaves? Not a popular bonsai subject because of that.

yes, I saw one on the internet once and it was beautiful. I was told that if you continue to cut the leaves in half that they will eventually get smaller. Is that true?

Yes, but there's more to it... like when, how much/many, etc. etc. Not something to do right off the bat (or for a few yrs yet anyhow).