mpirie’s advice is good.
You say “flip” and it’s not quite clear what actual action you are performing. I found that six sheets was easy to do. It’s probably easier to shuffle than flip.
Place each sheet individually into plain water. Don’t slide in as you’d do with paper. Put it on top, nearest edge first and push it under with your pinky finger. You need to do this so the film is lubricated.
Arrange the film across the tray so that they are held neatly by the sides. Place a batten under the far edge of the trays to give a gentle forward slope. This helps to keep the sheets in order. They can be very slippery and wilful. Put your fingers under the stack and slide the bottom sheet out and away from yourself, then place it on top, and push it gently under. Don’t press it down hard. Don’t slide it in; the corners are very sharp and wet emulsion is fragile. Go through the whole pile, counting as you go until you are back to the beginning. Do this at least twice. When your pre-soak time is up, you can deal them into the developer, and shuffle again. Your first shuffle should be for thirty seconds. I find that six sheets can be shuffled in about twenty seconds, without hurry, so two agitations per minute will be fine. Some people like to turn the whole stack round at some point to give more even agitation.
If you want to give different times to different sheets, you can either reverse the notches on one set, or keep careful count as you go through the stack. Best of luck with that, if you get distracted. That’s it.
...and so on, through stop, fix, wash and so on.
