My 6 year old finally got the hang of it two weeks ago. We have done some light off-roading (jumps!) and a tour of the East Swindon badlands, where you can cycle for miles on (occasionally glass-strewn) cyclepaths. I don't think she has the hazard perception to try the road yet, and she can't take a hand off the bars to signal.
We went out after dinner on Sunday evening. I had a wobble and had to do a quick drop down off the kerb (we were riding slowly on the pavement). I thought it was a pretty good recovery, but no.
"When I get older I want to drink too much wine and fall in the road," she said. Oh dear.