Commission is calculated as a percentage of profit - 15% of total profit per invoice. This is calculated and paid quarterly, in arrears. The commission is paid from the first penny of profit, no requirements to fulfill prior to being paid commission (other than ensure there is profit on an invoice). There is no cap on the amount of commission that can be earned.
Theoretically, I should get a quarterly commission paid at the end of July (for April, May, June) and then a further commission paid for the 13 days in August with my final payment.
Have you had a chance to look at this?