The easiest way to work out what flying can be included is to take the date you plan to fly, then add 1 to the days then subtract 1 or 2 from the years. So to fly legally today 24/03/2017 all flying can be included from 25/03/2015 or 2016 depending on 12 or 24 month window. On legal documents it always states a year and a day so thing happen on the same date every year.