As an add-on to what Assuiebear asked.

Where would these pieces of information be coming from?
When would this rename have to occur?
Would adding a button for the user to click, instead of the regular Excel save button, work?

Much more information is needed to try to assist you.

Here is some information that should help you understand what you're asking for:
Excel Add VBA Button - Automate Excel
Get Cell Value in Excel VBA (Step by Step Examples) (wallstreetmojo.com)
VBA Save As | How to use Save As Method in VBA Excel? (wallstreetmojo.com)