August test taker here, what people have said from the July test is we will create our ProctorU accounts while signing up for our slot tomorrow.

I'd like to think that timeline is feasible! I was in the same boat as you about 2 months ago. My initial diagnostic was a 148, I'm consistently testing around 160-161 with a 164 as my high this past weekend. You can make massive improvements by learning how to do the games, and in my opinion, in the right place to learn how to do them.