What I want to do is for example:
A time will be manually entered into a cell say D3, when it is 20 minutes before this I want cell D1 to change to "20 MIN", WHEN IT IS 5 minutes before I want to change the D1 text to '5 MIN' then when the time reaches now change to "IN PROGRESS", 25 minutes later to change to 'COMPLETE'. This same rule will apply for H - GS (as 4 columns are grouped together).D1 also has a data validation list that needs to stay available for manual override.
Will a script that can do this slow the spreadsheet down as well or not?
I have looked around for scripts but having no luck making it work.