---Please only post your questions once, thank you!---I've heard that you are not allowed to write on the scratch pad until the actual test has started. Obviously, it will help a lot to have this ready-to-go for test day before the timer starts. If you are worried about it, I would talk to the pearson vue center, or contact them directly (aka call them) and see what the rules are. My advice, follow the rules. 30-60 seconds is not worth having them cancel your test for breaking the rules. I've heard of it being done before for cell phone usage on breaks, but I've never heard of them doing it for writing on the scratch pad.
If you do decide to write on the scratch pad before the test, I would recommend doing it during a 60 second instruction screen that comes up RIGHT before the first question pops up. This would probably be the most opportune time b/c you could make the argument that the test had begun since there is a countdown timer. Buuuut, ultimately, don't break the rules b/c you could have your test canceled and a ethics problem will be posted on your GMAT score report, and could be a red flag to Adcoms.