When did he start doing that? Based on my past participation in his campaigns he uses the forum default timezone as the cut-off.
I don't know when he changed from forum time zone (UTC) to his custom time zone.
It is safe to assume that if a manager doesn't explicitly tell you to set your timezone according to theirs, then they will use the forum's default timezone. If you're too lazy you can also check your post and see the timestamp when it was registered on the forum (assuming you never touch the timezone setting). CMIIW.
If you don't have a very bad, busy week, you will not wait till last 2 hours to make your posts just to reach a required number for that week payment.
Hhampuz includes this message in his campaigns. He uses CET time zone. Start and end days of his campaigns can be different but time zone is always CET.
Each Payment will be sent to you on Mondays (Weeks will run from Mondays to Sundays CET Timezone).
Search with Google for time conversion from CET to UTC time zones, I easily find this information.
Central European Time is 2 hours ahead of Coordinated Universal Time