You need to gather beginning balances as of the conversion date you decide on. General ledger beginning balances are entered through the Maintain Chart of Accounts option, using the Beginning Balances button. In this way, financial statements, such as your Balance Sheet and Income Statement (P & L), will be accurate.
After you post a transaction to any general ledger account, you cannot enter G/L beginning balances in the current fiscal year. You can only enter beginning balances for the prior year.
When you enter beginning balances in your general ledger, you will want to make sure that your customer,vendor, item, and employee beginning balances total the amount shown in general ledger. (In other words, if you are using the Accrual accounting method, the accounts receivable total in your general ledger must match the total of outstanding invoices in customer beginning balances; likewise, the accounts payable total in general ledger must equal all outstanding bills.) The beginning balances for customers and vendors are not connected to the general ledger beginning balances, so you must check to make sure they match.