Userexit VF01 on Initial Screen

Hi,

I have a requirement to throw a warning message on the initial screen of vf01 when certain condition is met. I have included my logic in RV60AFZZ, however this userexit will be triggered x times (x = number of line items in the delivery doc). I've tried in RV60AFZC but same behavior. I need to show the warning message only once...

Thanks.