Would like some gentle opinions please, as I have no ideas about when to do this.

I am currently 12w pg and am a teacher. Work-wise, I have told the minimum of people (HR, the head, my department head and my line manager). I will tell other people as and when (and if!) they notice - was planning on telling my department just before Christmas, about 23w, although my line manager reckons some people may start guessing in about another month. (I hope not, hoping not to start showing until after Christmas, especially as I will be in drapey T-shirts, scarves and floaty empire-line tunics that I have worn a lot pre-pregnancy should I get any bigger.) I am also not having to move around the school at the same time as the students, so have little worry about being jostled in corridors etc.

In my last pregnancy, work colleagues were surprised to hear I was going on maternity leave when it was just a few weeks away. My uterus is inverted, so it grows inwards instead of outwards, so I am not expecting to get much bigger in the next 3 months, much like last time. I was also wearing pre-pregnancy clothes at term last time. So I figure it's up to me when to tell, rather than my belly.

I would like opinions from parents and teachers as to when to tell the students. I teach at a secondary school in a city, so there won't be emotional issues about little ones losing their class teacher with little warning if I don't tell them until later. I will have finished the courses with my exam students, so they will just be on revision time.

I was thinking maybe after Christmas (about 26w), but then don't want to have the less well behaved classes act up for a term before I go - hols start at 37w, mat leave at 39w. If I tell one class, the whole school will know shortly afterwards, so can't just tell my gorgeous ones only (and, let's face it, every class has some gorgeous ones and some slightly more high-maintainance ones). I could wait until I'm about 8m gone and tell them in the last week of term before the Easter hols, but they may well have guessed by then. Or I could wait until they figure it out and ask (no tact from several of them). The school I am in, although a city school, doesn't have violence issues so I am not worried about the baby's physical health.

As a teacher, what would you do?

As a parent, what would you and your child prefer?

As a pregnant person, what would you advise?

Thanks for any loving advice you wish to give!