Opening account adjustment

If you are trying to adjust opening balances of debtor with your book balance, you should try to reconcile it first, that is, try to find why the difference has arisen. Reason like delay in clearing cheque does not need any correction.

If the difference is due to his accounting mistake, he shoulld correct it.

If the difference is due to not accounting by you of sales returns, discount, expenses reimbursed, errors  (if you agree to it) etc, you can pass the entries as on 1/4/17(start of the year)