This is an old post, but I was looking into this recently and figured I'd chime in.
Depending on you needs, the easiest answer I could think of is by creating a drop down menu and referencing a function on another cell.
A10:A20 > right click > Data Validation
- Criteria = "List from range" > F2
- Formula in cell F2:
To insert a time and date into a data validated cell (
A10:A20 in this example), click on the drop down arrow and click on the time listed. This will input the date and time into the field and not change it each time the spreadsheet is updated. If you'd like to change the formatting of the cell to be just time, or just the date, it can be done easily (select desired cell(s) > Format > Number > select format).