Excel force date selection

I'm developing an Excel file for data entry by users.  The file has 12 tabs.  The data entry area in each tab is no larger than one page.  So, if I was to print the entire file, it would be 12 pages long.

I'm trying to figure out a way to force the users to select the month the data pertains to and have the month appear in the center header of each sheet.  Multiple months across the tabs cannot be used.  The month must be the same on each sheet.

I'm not trying to insert the current month but rather a selected month.   For example, the users may need to generate a report for say, July, 2017.   I want the users to be able to open the file and be forced somewhere along the line (possibly before being able to print or save) to select the month the data pertains to.

Basically there are 2 or 3 users involved; each sharing the file (in sequence, not concurrently) and each responsible for a few of the tabs in the file.   If the first user selects a month, then if all tabs are populated with that selected month, that would be fine.  Or, maybe each user goes through the process of selecting the month but the program looks at the month selected by earlier users and prevents an alternate month from being selected.

Any ideas?  Thanks.