I was wondering if the reset time on each day and on the weekly reset is set at one time (Australia time) with the only difference between players being time zones - why have some of my guild mates already reset but I still have 3 hours being on the west coast of Canada? Shouldn’t they still have 3 hours before reset but it would be a different hour of the night compared to me?
I believe guild resets are currently a tad buggy timewise. It’s slated to be fixed in the guild updates of 2.1 and 2.2 as far as I know.
The guilds definately have a few bugs that need to be worked out. 
Guild resets haven’t ever happen all at once, with different people in the same guild getting rolled over at different times. There have also been reports of getting more than one reset in a week, but I can’t personally attest to these. Prior to 2.0, resets would generally happen for everyone sometime on the day prior to the PvP roll over. With the time shift in the reset, some are falling before, and some just after the patch instead, which is often when the PvP rush to Tier 1 and accompanying donations happen. If you are in a guild with a weekly requirement, you should make sure that they are properly documenting through offsets in the all-time donations rather than weekly, or only donate after you know your personal weekly reset comes along.
I’ve always reset at the announced time for my time zone. My initial donations don’t show on the roster page for about half an hour after I make them but thanks for the concern.