How does the customer profitability impacted due to Sell side Channel revenue programs?

Typically, the customer promotions rebates accruals and claim generation happen at a later date ( post invoicing of Sales order).

How and when does the customer rebates impacts the gross margin or profitability of a customer. Will the customer gross margin change from what it was when the order was invoiced and later when the ChRM accrual or the claims are created?

Will it accruals/rebates appear on any customer level reporting?