How do we tell his parents that I'm pregnant?

Mo

My fiance's parents are pretty religious and are the judgmental type. They're also super controlling and want things to go their way, no exceptions. They don't want us to get married until my fiance is back from basic and tech school for the military. Little do they know that I'm pregnant though. They've come to accept that my fiance and I are getting married next year once he's back from basic and training and want us all to still be part of the family when we do instead of leaving them out of our lives for how they treat us. I really want to have a good relationship with his parents, and I know his little sister already can't wait for me to be her sister-in-law. However, not too long ago my fiance overheard his parents say, "wouldn't it be terrible having a little HIM (referring to my fiance) running around?" We were planning on announcing to his parents that I'm pregnant on Christmas and I'll be 12 weeks and 3 days pregnant by then. I put a picture of the ultrasound inside a card and on the card I wrote "We had our plans, but God has His!" along with a drawing of baby Jesus in the manger on it. And inside I wrote a heartfelt message expressing how we both love them and how excited and scared we were that we are having this baby. I also wrote how we hope that they will support us and that we know that it's a big step, but it's all in God's hands now. Should we continue on with this announcement or should we do it sooner or maybe later? I don't know what to do. My fiance is worried about doing the announcement because of what his parents said. My family knows about it and are in full support. We just are having trouble figuring out how to break it to his family.