For most users, when you toggle on the option to use "overnight syncing" the syncing starts at 6am UTC (which is 10pm PST / 12am CST / 1am EST)
For PCO clients, because of the "Auto Refresh" option that runs at 2am, we have adjusted overnight syncing (for PCO users) to sync after that refresh in PCO. We run our overnight syncing at 3 am PST / 5 am CST / 6 am EST. This should ensure we pull in the latest changes after PCO re-syncs the lists at 2 am PST.
Since then, we've noticed that some changes are not being synced well. So, we've added an additional overnight sync to catch anything that was missed.
The current PCO sync times are below.
NOTE: Since the three example time zones are now in daylight savings time, the zones are "D" instead of "S" (Pacific Daylight Time instead of Pacific Standard Time).
10 am UTC = 3 am PDT = 5 am CDT = 6 am EDT
11 am UTC = 4 am PDT = 6 am CDT = 7 am EDT
To check the sync times in your time zone, here is a basic time zone converter.