I've been running a game for three sessions now, and each time I feel uncertain as to how to raise the curtains, so to speak, to let everyone know that we're entering the magic circle and it's time for me to be the dungeon master and them to be the players, as opposed to us being just friends sitting in a circle. I can of course do something like say "Okay guys we're starting now, time to get serious", but this feels to me a bit heavy-handed, and I'm not sure it would help us all get to the place we're aiming for.
This is especially important as I'm going to be moving to a new place in a few days, and any players I find in the new game I want to run then might not be experienced players and have the presence of mind to consciously put themselves in that roleplaying state of mind.
What techniques can I make use of to put everyone in the right mindset at the start of a session and to provide that rigid turning point beyond which everyone knows the game is really on?