Need some advice....

Alright so I'm 5 weeks tomorrow. We haven't told anyone yet, but want to tell our parents soon. Thing is.... my parents live 2 hours away. Theres a big family supper planned at their house next weekend and we want to tell them there, but I have 4 other siblings and dont want EVERYONE there to know. They want us all there by 1pm... and we cant go early because we have an appt that morning that I cant change. But I KNOW I wont be able to hide it from them and they will think I'm acting strange lol.

What should I do?!? Try to get there a little early? Just tell my whole family? Try to stay the latest? I'm not even sure when we will see them next.