Adding a date stamp + other value to a text or string field

Hi Marketo community,

I would like to start adding some simple custom data tracking relating to interest/ intent someone has shown in a product, based on their interaction with a different activity (eg: Requests a product demo)

I believe the best way to achieve this is using values which populate automatically into a string or text custom field, using data value triggers in the Marketo campaign itself.

However, I would also like to add in a date stamp next to this value too, so I am able to track what month/year the action took place.

For example:

• John requests a demo on product X in March.
  • After this demo request triggers, the Custom Field, let's call it "Interest" for the sake of this example, populates as follows:
    
    • If "interest" is empty, update John's interest field to 'Product X March 2019' or can be 'Product X 03.19', or similar. 

Is there a way to achieve both items of information pulling through to the field? 

Many thanks