Hi IP2B
I have no idea if this article is true or will help, but take a look if you like:
voices.yahoo.com/how-induce-lactation-well-may-not-dry-217473.html
It seems like even men can lactate, may not be exactly want you want to read about but should give you hope....
en.wikipedia.org/wiki/Male_lactation
With regard to when/f to tell people can I just give you my own perspective? I am not an adoptive parent yet, but hope to be one day. I have a 7 year old birth child and for many years we tried to give her a sibling with IUI. IVF and laterly IVF with donor eggs. I seemed to go through phases of telling peope or not telling people about the donor eggs. In the end the treatment sadly failed so it was all an academic point but one thing I did feel coming through the experience was that you can never un-tell someone! By that I mean once you've told people it is out there, it is something true for you and also for the child but it is not necessarily everyone's business. It would have been a different scenario if we had succeeded ( to your situation) as I would have gotten the big round tummy etc. Ironically, I do already have a big round belly and I often see people trying to suss out if i am pregnant!
With the toddler group you may well want to explain how you have a new member of the family, I guess from my perspective I would keep it low key, new people will join the group and people will move on etc, I would not feel you had to tell everyone all about it.
People may be curious, they might ask if your egg was used in a surrogates or a surrogates eggs was used, or a donor embryo etc. I am NOT asking that I am just saying those are the kind of questions, so you might want to think how much you will want to talk about it.
I usually find if I want to share something but not talk a lot about it, I might blurt it out as I am about to leave 'Got to rush to catch the next bus, by the way next time you see me I will......'.
Surrogecy is not such an unusual thing these days (even if I am struggling to spell it!). I wonder if many people will probably know of someone who was a surrogate or had their child via a surrogate (sorry if I am not using the right terminology!), or will have seen a film about it or documentary (or might have totally wrong ideas about it!). They might have considered it themselves, either way, and so you may find lot of questions, or you may be in a place where people keep themselves to themselves and will simply nod and smile!
Whatever you decide to do, I wish you all the very best with your new baby and hope all will go well.