You just claim rewards once per day and automatically get 0-8 dust per day.

The 6h doesn't matter too much, it's enough to just claim every day once they'll get the dust for that day. It may get a bit confusing with time-zones and people who may leave it til the last hour to claim and realize they skipped a day due to timezones, etc, but if you claim once around the same hour daily you should be fine technically speaking.