How does the timezone/timestamps of sale notifications work?

The table below shows exactly what time stamps will merchant and affiliate receive after a sale is done in other timezone. Timezone set for merchant or affiliate depending on the last known login to their merchant/affiliate panel and the location from which it was made.

Customer makes a sale from Japan.  server with installed Post Affiliate Pro has by default timezone set to America/Los_Angeles. Merchant's last known login was made from New York and affiliate's from Berlin. In their panels they would see the time of the click/commission with different timestamps calculated based on their timezone.
 

Merchant	Server	Affiliate	Customer
USA - New York	America - Los Angeles	Europe - Berlin	Japan - Tokio
GMT -05:00	GMT -08:00	GMT +01:00	GMT +09:00
Merchant receives notification that the sale was made at 05:04 AM local time.	Transaction is saved into server database with time stamp 2:04 AM local time.	Affiliate receives notification that sale was made at 11:04 AM local time.	Customer makes a purchase at 06:04 PM local time.

Server time is used for sending daily, weekly, monthly email reports, when you are importing data via CSV, it can be selected when doing CSV exports, it is used for grouping of clicks commissions.

Change server time of your installation

You can set server timezone in merchant panel > Configuration >  Languages and Regional settings > Time Zone settings tab 

For older versions than 5.5.48.2, you need to add a setting into your Post Affiliate Pro database. Open the database and add a new record to qu_g_settings table (if there exists row with name: 'TIMEZONE' edit it):

example of sql insert command:
INSERT INTO `qu_g_settings` (`name`, `value`) VALUES ('TIMEZONE', 'America/Los_Angeles');

Note: In versions older than 5.0.9.5 this setting used to be in accounts > settings.php file, where you would add a line like TIMEZONE=America/Los_Ageneles