Someone will correct me if I'm wrong (they are nice like that), but I believe you need to maintain that level of performance for 30 days beyond the evaluation date and then if you do, you should get your new rating on the first of the month following that 30-day period.
For example, if you get that evaluation on June 20th and you maintain that level of performance, you should see a change on August 1.
Once again, if I am wrong, we will all know shortly. 😀
