Ask him if he would like to take a trip to Ireland to celebrate his graduation. I’m sure he won’t be starting work immediately, but if he already has a job it’s an easy excuse for at least a 2 week vacation. You could offer to show him around where you live and all the cool spots. Introduce him to your friends and do some of the things you all usually do for fun. Then you can take a trip to the touristy spots, which is conveniently a great excuse to get a room for night in the city, ya know, to make sure you have enough time to see everything and not worry about the travel time and such. Then for the end of the trip, just spend the time relaxing, and hanging out together. Give yourselves the time to get comfortable doing the day to day routine, give him a chance to experience what regular life in Ireland might be if he were to stay a bit longer.