The syncing of local AD to Azure AD typically runs hourly. If you want to speed this up however, log onto the machine with the Azure Sync Utility on (if unknown, have a look at the user list for “On-Premises Directory Synchronization Service Account” and the Usename for that account will be Sync_SERVERNAME_5c52d34efa74@clientname.onmicrosoft.com. The SERVERNAME is the server where the azure sync tool is installed.)
Open a powershell window and run
Import-Module ADSync
and then run
Start-ADSyncSyncCycle -PolicyType Delta
