7 weeks pregnant and starting new job soon. They don't know that I'm pregnant.

So, 3 months ago I was laid off from my job and had been searching ever since. I also found out last month that I'm pregnant. When I was first laid off back in July I had filled out an application for a direct support professional in a group home, but never heard back from them. Well, fast forward 2 and a half months and I had a phone interview as well as 2 face to face interviews. I never mentioned anything about me being pregnant and I found out today that I got the job. I really want this job and I'm so excited about starting soon. I'm just wondering when I should tell them that I'm pregnant. I'm afraid that if I tell them I'll lose this job. The group home that I will be working in is for people who can't live independently and have intellectual disabilities so some of them will need help with basic things like bathing. Any thoughts on what I should do? Should I tell them now, wait until after I start and act like I just found out, or just keep my mouth shut until I start showing? Thank you ladies!!!