Previous losses or not it's your decision when you want to tell people. It's a very personal thing, I know I gave friends who announce the moment they get their bfp, and others who wait until after their 20 week scan. I had one friend who didn't tell anyone until 25 weeks. I've had losses and tell my best friend as soon as I know, but that's because I know if I have another loss I need her nearly as much as I need my husband.
I was supposed to start a distance learning course in January with another girl at work. I dropped out as the first of the two exams dates is my due date. The girl I was supposed to be on the course with told me today that she's also had to drop out. She's a week ahead of me! Work are going to be thrilled! Lol.