I would create a section with one indentation, and place your pivot point smack dab in the center of your watch, and start making copies of that indentation and welding them until you have 1/4 of the circle. At witch point you can just duplicate it 3 more times. Good old fashion duplicate around the correct pivot. You can place your cursor right in the middle of the watch (you have to be really really precise) and switch the mode to pivot around the cursor. That’s how I’d do it. I’m no pro though.
EDIT: oh and also you can count those notches, and make a cylinder with that many subdivision to use as a guide for how big your first piece should be.