Hi OlgaP,
I would advise AGAINST writing anything on your hand for a couple of reasons. First, it won't be clear to anyone (other than you) what you're actually writing down - if anyone at Pearson/GMAC thinks that you're writing down information on Test questions (so that you can share that information with other people later on), then your score might be 'red flagged' or cancelled outright. Second, if you take your 8-minute break, then walk back into the Computer Lab with notes written on your hand, then that could be defined as 'cheating' (you're not even allowed to bring study materials into the lobby, so imagine what the administrators of the Exam would say about you bringing 'notes' into the Lab). Third, if you already know what your pacing 'benchmarks' should be, then you shouldn't need to write them down - you already have them memorized.
1) How long have you been studying?
2) When are you planning to take the GMAT?
3) What is your goal score?
GMAT assassins aren't born, they're made,
Rich