Have your time in and out of the WiFi network logged, the time you spent every day at work automaticaly calculated, the averages of arrival and departure times last week... in a google drive worksheet.
...And much more...
Here is an example: https://docs.google.com/spreadsheets/d/1tepTGjQQj_VbovZIqxhLc8Ua7CB2zvB6WC8rquSmjOk/edit?usp=sharing
