If your daily reset comes at an inconvenient time i.e you cant do your dailies after contest starts and before your next reset you should change your time zone. This does in fact give you an edge in the weekend contests (assuming its always going to be spend dia/stam or find items). You can get 5 challenges runs 2 mountain runs, an expo reset, a boss pit, stamina buys, fp and coli fights, and possibly some shop items which could mean 5 million points in an item contest depending on luck (mountain/challenges/boss pit drops), level (mountain/challenges/boss pit difficulty) and vip level (double expo/max boss pit/stamina buys) or just stamina buys and expo, coli, and fp (are those last three in a diastam contest cuz i dont do diastam contests) in a diastam contest.
In order to change your time zone you need to change your phone time zone as well. Daily reset comes at 5am. You dont want your reset to fall at contest start or end times. Contests start at 12am PST/PDT (someone please clarify if daylight savings affects start and end time) or 8am GMT (7am starting sunday march 11th but only if daylight savings affects it) so dont set it to utc-3:00/adt/gmt-3:00 or utc-2:00/gmt-2:00 to be safe. Now all you have to do is figure out a time zone that works for your schedule but basically you want your reset to be right after contest starts right after the first time you can play during the contest + enough time to do your dailies or right before contest ends right before the last time you can play during the contest - enough time to do your dailies