Isn't payment date mentioned in mandate itself? Generally they do send pre debit msg 24hrs before the transaction.
Woh toh due date pe debit hoti hai na? Sunday hoga toh next day yahi Monday ko hi debit hoga usse phle nhi.
Yes usually 2/5/10. Some time also happens in month end for corporate tie ups. In my father's case, company used to pay certain part of emi , so they used to deduct emi directly from salary.