Ideally, how soon should a company close its books? ( e.g. 3 working days after the last day of the month)

it will be closed every month end.  For accuracy & correction, accrued expenses will be transferred to next month. Closing balance of all ledger will be transferred. Stock taking will be held with month wise closing. Cash & Bank balance will be accurate. 

WILL BE CLOSE IN THE END OF MONTH AND THIS3 DAYS AS ADVANCE OR ACCRUED FOR NEXT PERIOD