Announcing to high school students

Allyson
Are there any high school teachers out there trying to figure out when to announce to their students? 
I'm 10 weeks now and I've been thinking about it a lot lately. 
I suspect some of them may know (week 7 had a lot of frantic bathroom runs so I didn't puke in front of them). 
I was thinking maybe around week 14. My next doctor appointment is at 11 weeks 4 days, so after that appointment is an option too. 
Thoughts?