Little Butterfly is now 10 months and is definitely communicating and interacting much more. She has learnt to wave, and does so whether people say 'au revoir', 'bye bye' or 'пока', but then of course she is also responding to the cue of people putting coats on, waving and going to the door so there are lots of things that help her work out what is going on.
Butterfly has also learnt her first other 'sign' - whenever she tries what to touch a hot cup of tea or when a mouthful of food is too hot for her, I have been saying 'chaud' (hot in French) and doing an informal sign. And now she does the sign herself. Hooray!
We've never attended baby signing lessons or anything, but I've found with all three little bugs that a few signs when they were small enabled a bit of early communication and were actually quite useful with three languages: Butterfly can see that waving goes with the words in all three languages, so this will hopefully help her work out that they mean similar things. Her dad can now use the 'hot' sign and say the word in Russian. We do a few signs for animals (along with animal sounds), and as these are constant, they can hopefully act as a further cue for her that the different words in each language mean the same thing.
I was speaking to some parents of a trilingual child recently, and they were surprised that their son (aged nearly 2) was able to cope with several words for a single thing (e.g. 'voiture' and 'car'). However, this sort of thing happens even with one language: children progressively have to disentangle 'bye bye', 'ta ta', 'see you later' etc. so adding an extra language or two is only extending an existing process of language acquisition.
I look forward to seeing little Butterfly communicate more and more over the coming months!