What's the best way(or correct way) to pre-load the Hosted and Mobile Databases with the same data so that way the first sync will only add the new records from the mobile devices? 

Edited August 17, 201510 yr by GisMo

A lot depends on what you are doing with the data. The first question is: Do you really want ALL of the data in the mobile device?

Tim talks about this a little in the beginning of this blog post: http://timdietrich.me/fmeasysync/docs-easysync-integration.php

In that same blog post, Tim mentions this about pre-loading the database:

If you are pre-loading data in the mobile database:
• Make sure that the values set in the ES_Record_UUID fields are identical in both the hosted and mobile databases. Otherwise, when the mobile users sync, you might end up with duplicate records.
• In the mobile database, in the EasySync_Payloads table, set the ES_Last_Push_UTC_Time and ES_Last_Pull_UTC_Time global fields. You'll want to set them to a value greater than the time that you loaded the records.

What's "correct" will depend on the situation, so you'll have to judge that for yourself. Here are a few methods:

1. Before deploying the mobile file, sync it. It may take a while to run, but at least it's only done once and you can be sure you have a fast connection to your server.
2. Import records via FileMaker's import dialog or write a script to do it.

If there is a lot of data, importing will be fastest.