Your requirement is not clear. Please post sample workbook along with expected results.
Day fixed basically assigned each date from the year to a lip year which provide you the possibility to compare across data on same day of the year. In this context you can ignore that. I am sorry that my company server is on 10.4, are you able to provide a more detailed answer regarding to how you figure this out? such as what is your input and what is your output.
My input here is only
2014.1.1 15 2014.1.2 9 2014.1.3 5 ... 2015.1.1 14 2015.1.2 16 2015.1.3 8 ... 2016.1.1 13 2016.1.2 12 2016.1.3 17 ... ... ...
Please share your sample data.
1. Calculated Running Sum first considering condition for >10
RUNNING_SUM(sum(if [Value]>10 then [Value]-10 else 0 end))
2. Added Year in a view based on available date to get results for each year
3. Get first occurrence of running some for each year.
window_min(if lookup([Value>10],0)=window_max([Value>10]) then attr([Date]) end)=lookup(attr([Date]),0)
1. Check if running sum within a year is maximum running sum value available for that year
2. Get corresponding dates and identify minimum date which is 1st occurrence.
I am not sure if this provides any clarity may be after looking at a dashboard, you can have better understanding.