Enabling O365 CRM Integration for events

Enabling O365 CRM Integration for events

Hello Everyone,
The help docs don't really explain a way to test this on a single user. It says that I can turn it on for users I choose which in theory will work but we have had other integrations with o365 that have just automatically attached itself my users in o365.

My question is for anyone who has done this integration:

If i were to enable this and get the o365 add in will it automatically enable everyone in my o365 org or will it give me the ability to have everyone turned off for the time being until I can test it and then turn it on for my users?

We are a franchise system and I have to test everything extensively before flipping switches otherwise I can royally mess up how our users deal with their data. I just want to make sure that I wont be trying to frantically deactivate the add-in because it enabled itself across our users.