it's when they are issued but be careful, Japan Airlines wouldn't let me fly until I showed them an email proof from my consulate that that's what it is. They were under the impression that it's 72hrs from the time test was taken. So, have proof of that - email your consulate and print that email.
Thank you. What was particularly good about it? Did the room have a nice view and were you allowed outside at all, such as balcony or to use any pool area?