This is what seemed to work on my Tink, she's almost 9 weeks, there was a recommendation when she grabs my finger, to push farther into her mouth, kind of "sticking" her mouth open gently, till she gets grossed out and tries to get my finger OUT of her mouth- it's working well, i tried the yelp, no dice, then I tried the NO,but we're working on a different naughty behavior with that one, and didn't want to freak her out with that word ALL the time-
I do it sideways, i don't choke her, just sort of like a bone sideways- and only for a few seconds-but she has gotten to the point where 80% of the time, when faced with a choice of my fingers or a readily available chew toy, she picks the toy...Thank goodness!