Depends, i guess.
IRL
(I've had plenty of experience with this, so I generally know what to do, and what feels natural)
The 1st meeting: is very visual. Mostly small talk.
The 2nd and 3rd times: would be all about breaking the ice, seeing if how we interact and if we communicate on the same level. AKA if we click and connect.
(It's at this point where I'd probably know, whether I would have romantic interest or not.)
4th-10th meetings: we get to know eachother better; share common interests and such. Become comfortable with eachother, be able to casually flirt with eachother.
8th-10th meetings: interact and mingle with friends on both sides, at this point dating just kind of happens, and hanging out at eachother's places (casually) would be fine.
Online
I HAVE NO IDEA!
(The whole IRL idea... gets tossed on its flank)
I know that sounds horrible, but it's true.
People are just so paranoid on the net... I'm bewildered when I hear of couples forming online. It leaves me scratching my head. I guess, I just try be as open as I can, try to get to know the person the best I can... and maybe, just maybe, if I see something there I may start flirting, and see what happens.