There are some parts of HTML5 that are worth starting to use now, I believe.
Canvas is overrated, I'd always use SVG instead, as has all the DOM event handling.
I am guessing that the date to start using HTML 5 could be sooner based on the influence and amount of coders that are using it. The more web developers that start using it the more the browsers would start to support it.
Todd Temple > T2 Design