For weekly payouts, payout is calculated on Mondays & then issued on Wednesdays. That can sometimes lead to confusion if you get a sale on Monday or Tuesday, after payout is calculated.  Any incoming sales after payout has been calculated on Monday will be added to the next week’s payout.

You can look up your sales totals on your "all activities" tab on the "stats" page to get a better idea of the timing of your earnings.