How can I automatically subtract a number based on previous 90 days (attendance tracker)

Originally Posted by JeteMc

This proposed solution employs three helper columns, any of which may be hidden for aesthetic purposes.

Thank you all for coming up with a solution. This seems to work. Is there a way around the following problem... (updated attachment showing issues below)

Today is 8/8/2017. If someone was hired on say, 8/1/2017. On 8/2/2017 they have a NCNS (5 points). (row 6)
Currently with your solution, their total points are at 4 instead of 5. Is it feasible to only start at the employees date of hire?

Another example: Hired 1/1/2017, NCNS on 8/7/2017 (5 points). 1/1/2017 - 8/6/2017 = 218 days perfect attendance. (Total points should be 3 due to having two 90 day periods perfect). Currently this example totals 4 points. (row 8)