When you connect your Fitbit with World Walking, our system automatically syncs every 24 hours or less. Once World Walking has pulled in distance for a particular day, we only bank the difference if more steps were added to Fitbit since our last check.
Every time you sync your Fitbit device with the official Fitbit mobile app, your World Walking account receives a notification and should automatically sync in the background. Failing that, we'll check every 24 hours and pull in any steps we might have missed since yesterday. For more information on how to sync your Fitbit device please see https://help.fitbit.com/?c=Topics%3ASyncing
If you have any issues with Fitbit sync, please first check the fitbit.com website (when logged in) under Log > Activities, then Week > Distance. The totals in kilometers should match up with what has been automatically banked in World Walking.
To stop syncing with Fitbit, just disconnect in the Settings > Apps page.