I have tidied up the link to drlazone's video. Hopefully you'll be able to see it.
Basically he's starting on a 65ltr/-25ltr board. He uses the front handle, not the flag handle. Basically he gets the wing out of the water and into half flying position before gets his knees on the board, gets the wing properly flying, then away he goes.
I have had a couple of practice sessions on a 40ltr kite foil board. I have not had a successful start yet but I learned a few things. I did one session with no wing. And one session in stupidly gusty winds with the wing.
As with most people the first few goes were hopeless, but with a bit of practice I found it surprisingly easy to get my feet on the board, the front foot in the strap and the board sunk and stable. As long as I stayed put I could have stayed on the board all day. As soon as I moved to lift the wing I would roll off.
Other videos have shown people leaning on the leading edge of the wing, which is what I tried. I had no luck at all getting the wing off the water. I couldn't work out how to effectively practice with repeated failures without ending up munched by the shore break or dragged into shallow water. I didn't want to risk gear or waste prime wing foiling conditions messing around in the shallows.
The get the wing partially flying trick looks promising. I can visualise how that might work and that's a big first step in learning things.