If you've got your target score on the GMATPrep, I'd schedule your test-date. There's a fine line between keeping up the skills and burning out. If your target score is 650, I always tell students to aim for 700 to be "safe."

I would take one test each weekend and keep practicing. There's no need to sit more than 1 CAT a week. On the last 3 tests, make sure you do the AWA to practice doing those in the timing guidelines using your planned template. That way there'll be no surprises on Test Day. You'll also want time in between each CAT to thoroughly review all incorrect questions and log them in your Error Log by concept.

Keep rotating concepts -- if you do DS and SC one day, work on RC and PS the next. Don't let more than 2 days go by without "hitting" all the question types.

Since you have 3 CATs left, I'd schedule your test in 3 weeks, and keep seeking out the toughest questions you can find. There's a bevy here on BTG!