Is it possible to create a template that can pull the information from a required filed and put it in the subject line of the request?

So for example we have an Add User template that we created for new employees. One of the fields that is required is called Effective Date and Time. This is the day and time that they will start. We would like for the Effective Date and Time to automatically replicate in the Subject Line of the request once it is filled in if possible.