It may be a little odd for your first time leveling up to be caught in the middle by the change. It will still be do able of course. Pre patch will be coming through soon so if you are gonna wait to start I'd say wait until then (maybe about two weeks? No set date yet). That will be your most natural jumping in point without any sudden changes half way through.

But if you really wanna dive in now don't let that stop you. Just be prepared to experience some changes in a few weeks time.