It finally happened

I finally got the promotion ive been waiting for.....the past year ive work hard to get promoted to manager! its only a temporary posistion with a raise😁 however im 9 weeks pregnant and havent told work....should i have told them before i accepted the position? I feel like if i told them before they wouldnt of offered it to me. Im waiting till my first trimester is over....is that reasonble?