I was told to save it to my desktop so I can use it on a weekly basis.
If you will be using the same excel sheet week to week I recommend saving a new copy of it each week and saving it with your records.
You can help protect the original empty excel by marking it read-only and saving a new version of it week to week with that weeks time entries.
You can also keep it safe by storing a version of it online in a service such as Google Docs or Outlook Drive in case something happens to your computer.
Please let me know if you have any questions.
Thank you, -Ray