A significant event that can arguably be identified as the critical turning point for Gilly's life is the receipt of the The Lord of the Rings Trilogy by J.R.R. Tolkien. It was from the books that she learned the origin of Galadriel, even inviting Miss Harris to call her Galadriel. It can be argued that embracing a new name spurred changes in Gilly and precipitated the turning point for her, that in addition to Miss Harris taking so much positive interest in Gilly that she initiated writing Gilly letters:
I ... miss having you in my class, ... I hope ... that you are enjoying your new school and that the people there are enjoying you, as well.
I certainly won't forget you even if you never write, but it would be good to hear how you're getting along.
In confirmation of the the books and Miss Harris's interest being the turning point for Gilly, it is as Galadriel that Nonnie introduces Gilly as they start their new adventure together and as they wait for Courtney to come. Nonnie being "rinsed and curled" and Gilly being "cut and blown" is a metaphor for the big changes--good and not so good--that are to sweeping over them leading to an optimistic, permanent reworking of Gilly's life, her life as Galadriel. Their Christmas tree confirms their new lease on life after the turning point:
Nonnie slipped her glasses on and off her nose, trying to take in the sight ... while she clapped her hands .... "I can't remember ever before having such a lovely tree,"....
Neither, after she thought about it, could Gilly.
I would say that there are many small turning points in the text but I think overall Gilly is portrayed as an angry, abusive child gradually transformed by the love and stability she experiences while living at Trotter's.
the turning point in the great gilly hopkins is that she goes to san francisco where her mother Courtney is and flies there by herself and meets her mom.
The most significant turning point in Gilly Hopkins life was when after she was moved to Virginia and her experiences with Mr. Randolph and Miss Harris that make her change her perceptions about blacks and dwell deeply into his racist feelings, feeling shameful for judging people based on their skin colors. Her foster mother also bring about a big impact to her life, as she had witnessed her whole-hearted concern towards another fostered child and feel deeply grateful for what a mother she had been. It changes her views on reality and gives her new hope to the future