Based on Marc Haime Idea 

https://experience.dynamics.com/ideas/idea/?ideaid=71b542ec-e0a3-ea11-8b71-0003ff68c1c4

It would be useful for notification recipients to receive an email each time an environment (Production or Sandbox) is created or deleted within a tenant.

It would be of further use to have the created time:date visible for the environments in the tenant admin console.

Thanks

and the answer given :

As Application Insights is set on the environment level (as opposed to the AAD Tenant level), and as Application Insights would not be set up at the time the environment is created, we do not have plans to support a similar signal for environment creation.

Could it be possible to set the application insight at Tenant level get this information available in Telemetry and notification ?

Or by any other way.

It would be really appriciated when we're creating UAT environments from Production.

It has happened that someone has created a UAT environment and we (administrators) were not aware of it, with the result that post-creation actions were not completely finished (account activation, configuration change to point to the UAT, etc.).

Best regards.