Please find my solution attached.
Below is steps
1st, left join your data to itself by using the keys shown below
2nd, create calculation fields as shown below and build the view.
BTW, according to my understanding in your excel, when January, the previous team default to itself.
Hope this helps
Book2_v10.2.twbx 14.8 KB
This was a good attempt but it doesn't exactly produce the view outlined in the excel therefore the main issue remains unresolved were I to proceed with this code.