This is a copy of that form. It could be on paper, a database or any other method you chose as long as you have the information. The next to last line is about your time estimate. Once, because if you did it better than that, the new time is your best. Maybe one out of 100 times you equal your best time.
T o is when everything is clicking.
Rarely, unless there are serious problems in your organization. Hopefully, it is equally rare that you approach this time. This is based on experience, knowledge or best guess. This may sound odd until you realize that we are looking at a statistical range of times. Your most optimistic is at one end and the most pessimistic is at the other.