When to tell someone struggling with infertility?

My very good friend and her husband have been struggling for years with infertility, and recently went through IVF for the first time and had a chemical pregnancy. I got married last month and found out 2 weeks ago that I am pregnant. I want her to be the first among my friends to know about my pregnancy but I also want to be sensitive to her feelings. How much time should I give her before I break the news?