Cell(Column) modified date question

Question

I would like to know if there is a way to know when a cell has been modified and to store the date and time in a new cell. Here is all the case: I have a list, that need to be filled when an event occurs. After that, a person, need to follow up on this event and to fill "First follow up" field. There should be another field that stores the date and time, when "First follow up" field has been filled.

I tried few things, but it's a litle tricky, because the field that stores the date and time when the "First follow up" has been filled, should not change once it's set.

Any ideas?

Answer 1

I think you'd need a workflow for this scenario or use versioning on the list. I'm not entirely sure which would be the route to use since I don't fully understand the need/business process.