The security tables are on opposite ends of the esplanade, a big open area between the parks. The turnstiles for each part are on opposite sides from each other. So if you see it as a big square, two opposing sides will be bag check areas, and the other two opposing sides will be turnstiles.
If you get there before the bag check people are there, you *could* just walk through and wait in line at the turnstiles.
But you do NOT want to do that. Because by the time they tell you to go back to bag check, there will be a long line and you'll get to go to the end of it.
So if the bag check people are not there, just wait there at the little tents with the tables...even if people go by you and go through, know they'll be kicked out. Just wait, and be among the first to get bag check done, once those CMs get there.
I really like using the google satellite/map hybrid views for things like this, by the way. Just plop in "
disneyland anaheim" to googlemaps and zoom in until you see it all. It's a REALLY cool way to get your bearings!