Fiona is getting reluctant to go into her crate and while I am not opposed to giving treats I am concerned that if she gets one every time then it will take one every time.

Using treats at Fiona’s current age (4 months) is a good thing. Always say “crate” as she enters. This command will imprint on her and when you start your formal obedience with her she will learn the concept of doing as you tell her to do simply because you tell her to do it. Treat training is a gentle and positive way to get a puppy started on a good behavior.