If you've been studying for a while, take the last 1-3 days off before saturday. Cramming will just boost your anxiety. Topics that you have not seen before will probably just make you more nervous and chances are you likely will not see it on the test or you won't retain enough for you to solve the problem. If you don't get anxiety though, go for it
Review the Reference manual.
Seeing as its only sunday, take another practice test asap. Don't take one near the test date or you'll feel burnt out.
Get a hotel if your location is far away.
Eat a good breakfest.
Start going to sleep around 10pm, wake up at 5am seeing as how you have to sit at 7:15.