automatically mirror =NOW value from one cell to another

I am using an excel file to upload data to a database. During the import specific cell values are entered to the database.

At a point during the import process the database looks for cell B31. If B31 contains a date-time value (yyyy.mm.dd. hh:mm), it will upload it.

I would like B31 to be the date and time retrieved by the NOW function. However I can not have the formula in B31, because the import process will give me an error.

Is there a way to have a different cell (C31 is fine) that has the formula =NOW, and somehow the value will be automatically mirrored to B31?

Thanks