Hi Kum,
In fact there are at least to common methods to control hiring date. One is using a PCR and second in using customizing of V_T559L.
If you would do this thru PCR you have two options. First read hiring date from IT0000 and second is enter hiring date into IT0041(Date Specifications).
If you would customize quota generation you should enter hiring date into IT0041(Date Specifications).
It's your decision. Each has its own pros and cons. If you use first method and IT0000 there is no additional task like keeping hiring date in IT0041. If you keep hiring date in IT0041 you can simple define a quota generation rule just for run in first month of hiring.
Anyway,you can read hiring date from IT0041 by HRS=YDxxxx and from IT0000 thru HRS=YSxxxx. Have look help of HRS thru PE04.
If you would keep hiring date in IT0041 and customize V_T559L. You should create a specific rule for first month of quota generation and fill "Accrual Period" tab monthly and select "Rel. to date type" and select your subtype of IT0041 here.
Regards,
Omid