So effectively, if it's a new row (i.e. if column 7 is blank) add the timestamp to column 5 or 6 as appropriate, and to column 7. If column 7 already has a timestamp, just change column 5 or 6 as appropriate?

It looks like you might have uploaded a sample file to the forum, but not attached it to the thread, so we can't see it.

You might have to upload it again and attach it to the thread, if I remember correctly, they are automatically deleted after 10 minutes if they haven't been attached to a thread.