Create a date time stamp, and combine multiple columns into one new column

[JPAEP]

I'm not sure how this can be done, I know how to do it in Excel, but will need this done on a monthly basis.

I'd like to create a column named Actuals, Also, create a column with the date (01/01/2021 for all January). That's the easy part. So, where I'm confused is for any column that says ACT 2021-01, I'd need the new actual column to have that data, and the MM.DD.YYYY time stamp in the new date column. Then, i'd need all of the data in the blue to 'repeat' have a date stamp with February and the actuals have the data of ACT 2021-02.

Any help is appreciated and I can further elaborate as well.