When to tell work?

So I just recently started with a new company in December and am now 7 weeks! We have been keeping this our little secret until our formal wedding celebration later this month, where I will be closer to 11 weeks. Including all fam and friends! Just want them to focus on the wedding first :)
My question is- when do you tell your employer? I'm terrified. My boss has children but demands a lot of time and really acts like pregnancy is a burden (at least to my previous coworkers) in fact, none of the girls that took maternity leave ever came back! She's not a monster and her and I are close, I just feel she will be disappointed because I JUST started with the company.
Any advice or stories to share? I want nothing but positive vibes for my little nugget.
I also feel my best friend will feel the same way. She is so anti-babies and feels my husband and are rushing into things and she is so prpttective of me (we dated a year, engaged a year, eloped in November and now wedding this month) so a little over 2 years- but he's 35 and I'm 30 so it's not like we are spring chickens! Just bracing myself for the backlash...