To tell on Christmas Eve or not to tell?

I can't decide if I want to tell my immediate family for Christmas that I am pregnant. I will be around 8 +5 days pregnant and don't have my ultrasound until the 31 and my first appointment isn't until January 15th. We go to my husband's parents' house every Sunday for dinner along with my mom. ( my mom lives with us and as far as I know, she's still oblivious to me being prego) His brother comes home from Africa in February but will be able to face time with us then. His other brother will be here that week and the next as vacation time in the air force and probably won't be back in the state until August (est due then) as he is lucky if he can visit 2 times a year. I'm scared it's too soon to share, but I also don't want to keep it a secret much longer as it's been hard and everyone will be there. It's going to be their first grandchild. My husband rather tell them because he has already almost let it slip a couple of times.