My girl is one year old tomorrow and can sort of walk, she loves riding her dragon rocking horse and I'm starting to think about balance bikes.
Am I being a bit ambitious?
You're not being too ambitious, but why the rush?
I didn't sit on a tricycle (fixed-gear, FWD) until I was three or four. My children didn't sit on a hobby horse (which might be similar to a balance bike)until nearly three, over three in one case. All three kids (now 13, 16 and 19) ride with enthusiasm. There was no hurrying-along or encouraging. They just had the bikes to hand and quite liked the notion.
It is admirable that you are thinking about these things, but there are a lot of amusements and distractions in childhood and toddlerhood.
Bicycles are one of them. Play-Doh is another. Painting seems popular too.
The thing that will make them keen cyclists (if that's what they're going to be) are balance, flexibility, good general health, a degree of physical resiliance and a sense of curiosity.
They can get all those things from just fooling around in the garden.
It's wonderful that your kids have parents who think about these things and look to do the best, but I really wouldn't be in too much of a rush.
