Suggestions on how to reveal to SO

Im beyond excited and nervous at the same time like its not true.. I am about 4 days late and being late has become a norm for me since May. So this morning, I woke up and decided to take a test and it was positive and came up right away... I also went to my nearest clinic to get it confirmed and indeed I am 4weeks 5 days pregnant..We have been trying for a year and 7 months... I haven't told my SO yet in hopes of getting help from you all on how to tell him...His birthday is Thursday, but i want to tell him at his birthday dinner Friday. Any suggestions?