Provided you have followed the steps to activate the sync, it should take about 2 hours.
9 Activate Central Sync
The first time you promote a release, you need to comment on the OSSRH JIRA ticket you created in Section 3 so we can know you are ready to be synced. We will review your promoted artifacts. If no problem found, we will activate Central Sync for you and close your JIRA ticket.
After Central Sync is activated, your future promotion will be synced automatically. The sync process runs roughly every 2 hours.