I also can't see it any other way. Also the birthday of a person doesnt even need to be near the potentially missing date for the same 'conundrum', two people a couple of years apart but otherwise the same birthday who comit a crime on the same day in july (but in different years), the day before they becomes 18, will also each have lived a different number of days. I think they should both be treated as not yet 18, even though they don't have the same age in days.