Once stopped, BOTH feet on the ground, with engine in 1st and ready to roll to safety if needed.
This is good practice, at the very least until the car behind you has come to a complete stop.
As for taking off, it was start bike moving and lift BOTH feet up immediately, as soon as the bike had any motion.
Unless your right foot is already on the peg?
While stability is better with both feet on the ground, if the ground is flat, I find that if the ground is uneven, or rutted up ( not like that ever happens on our roads
) that sometimes you're asking for a drop by expecting both feet to be safely down. Of course, for riders over 5½ feet, this may not be an issue.
I pretty much follow as taught other than I will put the bike in neutral at a long light so I can drum on the gas tank. And of course, if trying to use my hands for something important (like a crucial picture or applying lip balm!), lean on left foot to use right foot on brake since hand not available.
Tappin' a long with a little "Ain't that a Shame"? I find I sometimes need to rest a wrist or two if I've been in stop and go traffic, so I take that opportunity to shake them both out. Especially when I ride with bad form on the 919, and put too much weight on my wrists with the new bars.