Example:
Suppose user lock bend at the current time Mon Apr 18 2022 06:40:39 GMT+0000
Then the timestamp is 1650264039
Current epoch week = 1650264039/604800(seconds of one week) = 2728.6111756
So the current epoch week 2728 starts on Thu Apr 14 2022 00:00:00 GMT+0000, and ends on Thu Apr 21 2022 00:00:00 GMT+0000
And next week 2729 will end on Thu Apr 28 2022 00:00:00 GMT+0000, when the user's first fee will be received