Prevent user from creating item and hour forecasts in projects


I have a requirement like users should not create/modify any item forecasts (or) hour forecasts on the last day of every month and they can create/modify in case they get approved by their manager.

Can you share me the ideas how can i implement this? I know one way is to create a custom work flow. Is there any other way we can implement this security.

Thanks for your help in advance!!

I don’t think handling with security is a good option for that or neither you can achieve your requirement fully with that . The workflow will be a better option.
I think project budget already has workflow.