First I would be sure that timming wise that that is the best time to tell him. He needs to know before a lot of other people so someone does not let it slip, but not before you are far enough along that the chance of miscarrage is a little lower. We had to tell DS about loosing a baby and it was not easy. Second be prepared for a positive or a negative reaction. At 6, being an only for quite a while is pretty much his life. He will most likely be trilled, but you need to be prepared that he might not. I would want to be sure that you are alone and have time to talk when you tell him. Not rushing out the door to the parks.
Now all that covered it could be great fun to surrprise him in some way. What about an "I'm the big brother shirt". You could even get a presonalized one done with something like "celebrating becomming a big brother at WDW". That would get him lots of attention in the parks. I like the big stuffed animal for him and a small one of the same kind for the baby. Would be neat for him tp tell the baby the story later!!!!!
Prayers on getting that little one!!!!!!
Jordan's mom