Y said her third school term would start in the final chapter, which implies they passed the Summer and Winter breaks, which would fit that theory, right?XY's timing depends on the academic term system in Kalos. If it adopts the Japanese academic term system, XY (epilogue) will end in January.
I wish that they match their game counterparts 's ages......as Y seem look like She is a late boomer to meY's birthday is in February, which means she's almost 13 in the epilogue. If that was before the March in BW2, that'd make her older than both BW2 kids. With X it depends on whether you consider him 12 in the main arc in October or in the epilogue, he could be the youngest or the oldest. IIRC Pokespedia wasn't consistent on whether the ages were for the beginning or for the end of the arc.