Early Effective Date

I am attempting to put my mind around Early Effective Dates.


Early Effective Dates are primarily determined when the disability arises to a compensable amount or  the date the claim was filed.  Which ever is later.


So in 38 CFR 3.156c, if the newly introduced medical evidence is used to grant service connection, is the Early Effective Date based on the evidence helping to prove service connection or the date the disability became compensable?


A disability could possibly not be compensable in 2015 by VA standards; however the missing record would have still made the claim meet the CALUZA standard and service connected at 0% in 2015.


Or is it because the missing record actually contributed to service connection and disability arose to 10%compensable  in 2018.


 The Early Effective Date would be 2018 with backpay of 10%.


All replies are welcomed………