First 50 bills for the customers will get discount

Hi Experts,

I am creating a promotion in SAP POS like First 50 bills for the customers will get 20 percent discount for a particular date range and as the 51st bill created this promo should not apply

I am unable to create this promo. Is it possible to create this promotion in SAP POS (SAP Triversity) and if yes then what would be the procedure to create this promo in SAP POS (SAP Triversity) ?

Prompt response will be highly appriciated.