User Configuration > Administrative Templates > Microsoft Office 2016 > First Run
User
HKCU\software\policies\microsoft\office\16.0\firstrun
This policy setting determines whether the Office First Run comes up on first application boot if not previously viewed. If you enable this policy setting, the Office First Run does not run on first application boot. If you disable or do not configure this policy setting, the Office First Run about signing-in to Office comes up on first application boot if not previously viewed.