CDO

Hi, I have one .nc daily data starts from 1979-01-01 to 2019-12-31, while I am sorting out the seasonal data using the splitseas, I found that it would sort the January and February and December in one year, however, what I really want is to use the D in last year while J,F in current year, I wonder how should I do? Also, after seleting the data, if I want to calculated the multi-year percentile, can I use the yearpctl to such DJC series?