Be in place on the beach at or before sunrise, and work the dry sand areas where blankets are laid. Assuming you've started around 5AM, by 9AM you should be ready to move to the wet sand areas along the shore, there the ground is flat and you can move faster. By 10AM you should be about done, get some lunch (in your car). Then set up the CTX (or whatever you use) for water and by 10:30AM be in the water detecting. I work parallel to the shore to keep the water height even, start near the shore, walk 100 yards or so, then go deeper and return. If you're over your head at some point you've gone out too far.
Hitting the water last gets you out of the way as people set up on the beach sand and puts you in a cooler place during the heat of the day (plus visibility on the sea floor is better). You can stay in the water all day if you had the energy and battery life - almost no one is going to bother you out there, even if the beach area is crowded. You should be out in chest deep water by the time most people are in the surf.
By 2AM you are probably ready to go -- I know I am after about 8 hours hunting. When you leave, switch off your machine and walk straight out of the water for the parking lot. Don't forget to smile.
Jackalope