Ah, "centered"... sounds so zen
I think routine helps. Its comforting in a way. Theres so much craziness/randomness/can't see it coming/be ready for anything type stuff at work that routine where you can get it helps.
My own: wake up, shower, put on some tunes, dress, anticipate order at starbucks (I only drink it pre-work, rarely on non-work days), drive, make order at starbucks, drive to work, "load up" my pockets once there (pens, trauma shears, gum---the 3 must haves, I throw in extras as needed) enjoy the 5-10 min before I walk out of the breakroom sipping on my starbucks mentally preparing, say a quick prayer if i think of it, take a quick look at the waiting room and department on the computer, throw in an extra prayer if its bad, take a deep breath, and go.
And those times you said you feel "distracted/ out of focus" are usually caused by getting overwhelmed by how much you have to do. Thats when you STOP. Take 5 seconds, breathe, realize that you are one person, you can only do what you can do, prioritize your tasks, and restart, knocking them out one by one. Its much more effecient to do your tasks deliberately and completely than trying to do 100 things at once sloppily, incomplete, haphazardly, and stressed... u know?