It varies with every dog.
The way I have always taught my dogs is with their kibble and it sounds the same as what you have been doing. I take their food bowl every meal and remove 25-50pcs.
click, kibble, click, kibble until all the pieces I reserved are gone then I gave them the balance of their meal in the bowl.
My guys usually picked it up in 2-3 days. You will notice she starts to anticipate the kibble as soon as she hears the click. If you were feeding from your hand she may look at your hand, if you were dropping it on the floor she will look at the ground when you click. If you wait just an extra second she may even look at your face to figure out why you are broken and haven't dropped kibble yet... that's when you know she understands click = treat.