If your sales are spread across several months, A*zon will pay you for each month separately.
Another thing to look out for is the country of sale. When the figures start appearing on your payments page, they don't all appear at once. You will receive payments for each site separately, often appearing on different days.
Last month there was mass panic because some of the sites appeared up to a week after the first ones. People were contacting the zon left and right, when there was nothing wrong. It was business as usual.
If you are expecting all your payments (correctly) to come out this month, and you're looking at the 'payments' page, be a little patient, and hopefully, by the 29th, they will all have appeared as they should.