You should take frequent Backups and keep several generations.

These can be entered or imported. In either case, they should be batched, so that you can check and adjust them before posting.

To keep the number of Transactions to a minimum, it is preferable to time the changeover to at least a Period End, or preferably a Year End, and to try to reduce the number of open Transactions to a minimum.

You should make sure that you have adequate Control information before you start - Trial Balance, Profit and Loss, Balance Sheet, possibly Detailed Trial Balance, Transaction Listings, Customer, Supplier, Stock etc. Balances and so on. You must be able to prove that the new System matches the details of the old.

As each Batch of Transactions is keyed in or imported, check the batch Controls. Keep Batches reasonably small, it makes checking so much easier.

If importing, it is a good idea to import each Batch into a copy of your data file, so that it can be validated and checked, and when it is known to be clean and correct, to import it into the live file.

For obvious reasons, the transfer of live Transactions is subject to similar considerations as Balances. In addition, since the numbers involved are likely to be greater, the use of the Import Utility is often essential.

All Transactions imported should be batched, and should not be posted until their Control information agrees with that taken from the old system.