We told her pretty much straight away, I was about 5 weeks.

TBH, the notion of miscarriage never crossed my mind, as it didn't with DD1 either. She was about 2.5 at the time, and well and truly capable of understanding.
We had asked her before TTC what she thought of it (about 10 months earlier) also.

Charlotte was so excited and spent the whole pregnancy kissing the belly and talking to the baby, she came to all the U/S and a couple OB appts too, heard the heard beat and all that jazz, she loved it. And I think it has really paid off - she was involved in the whole process and is so involved with the baby. She isn't jealous and understands, likes to help etc and I think a lot of that has to do with her being involved in the pregnancy.

My only regret was that I didn't have a birth she could be apart of.