I've found opening up about my stutter has been so freeing in relationships and it sounds like you are already comfortable speaking to him, so if you feel comfortable maybe talk to him a little more about your stutter on the phone before you meet (ex. How our stutter gets worse if we're nervous or tired and whether you like people to finish words for you or prefer to wait patiently if you have a block). Most people are super understanding when they understand it a bit more! Good luck and have fun!!