New game + question for Remaster.

I believe I am currently on a 4th play-through, haven’t played the game in around 3 years. Loaded the game up after the announcement, I’m right at the end of ACT 1. Do I have to finish the game in order to start a new game + for the remaster? Or can I just wait until sep 29th and load a new game + straight away? Not too sure how it works. Thank you.