Transitions
How are transitions from one subject to the next? Be sure students are equipped themselves to be ready for the next thing. Create a routine and consistently implement the everyday activities. So much falls into place if you smooth your transitions. It's easy to do the same ones everyday, too, so you have an expected and consistent routine.
Do you have DEAR or SSR right after lunch? Books should be on their desk ready as soon as students return from class--their job is to come straight in, sit down and read.
Do they have a folder for writing or workbook for math? Even if you are teaching or doing a lesson first, a good way to transition is to have them get that item ready, without opening it, so you won't have to wait on anyone when the time comes to scrounge around in their desks. As they move around the room (i.e. doing activities away from their desk) give them a specific job to do as they return to their desk, even if it's just sitting still and eyes on the teacher.