Salesforce Integration Initial Sync

I am currently in the process of testing how to set up the initial sync between Epicor and Salesforce for when we apply it to production. I was able to get the system up and running after clearing out the initial errors, but it did not sync all the Accounts and Contacts from SF to Epicor like we thought. I believe it is because the integration only looks for new/updates after its last sync datetime stamp. Once an update is made to the account it comes over. I wrote a batch update in SF to force an update to Account and run a regen, but that doesnt seem to be working for all accounts. How have others handled this initial sync?