How to announce to fiancé whose in Air Force basic training right now!

So i just found out I’m pregnant! I’m 4 weeks 3 days due date February 14,2019! My fiancé is in Texas right now for Air Force basic training. before he left we talked about it and i had told him if i become pregnant do you want to know or it be a surprise, he said yes tell me! I am going down there in July 19 to watch him graduate and we have planned on getting married then. Should i send him a Father’s Day card with a Cute little picture or should I wait until I get down there to surprise him!