I will try to give you a subject by subject overview of my experience (My mom home schooled my siblings and myself using some Abeka, and I taught in schools that used it for 14 years.)
The Abeka Language arts program includes their language, phonics, handwriting, reading, and spelling books, I believe. Depending on how she does with phonics already, you may want to skip the Letters and Sounds books since this teaches phonics. I do think it is a thorough phonics program, and some kids who read well still need phonics practice.
In first grade, their Language book does not deal so much with grammar, but mainly writing sentences. By 3/4 of the way through the book, she would be writing whole page stories. That may be asking a lot for a 3 year old, but as her parent you would know best if she could handle it.
By 3rd and 4th grade the Language books begin a very advanced grammar program. In my opinion
it is the best as far as grammar is concerned, but it seems rather weak in the writing area. That can very easily be added on your own though. I plan on using it for grammar when my daughter is older.
Handwriting: should be no problem for most 3 year olds. Reading: In my experience, most first graders find the stories boring, but they still struggle with reading the words, so they must forge on!! As an advanced three year old, she may find the stories more interesting, but too easy to read. They start with simple CVC word stories and progress through all their "special sounds" that the Letters and Sounds book covers. She probably wouldn't struggle with the special sounds even without the L&S book since she reads well already.
Spelling: might be pretty advanced for a 3yo, depending on her vocabulary. It might be a great way to broaden her vocabulary if that is what you want. Most kids who don't have the early learning advantage really struggle with Abeka spelling.
The Math book is great IMO. It does keep kids' attention with bright colors. If she already does well with math, the first grade book might be a good place to start. I plan on using it with my daughter in between other things (Jones Genius, Right Start, Saxon, etc) in a year or two.
As far as the History, Science, and Health books are concerned, I think the first grade might be good for a 3yo, but use your discretion on that. In my opinion again, they don't push a kid to learn much actual subject matter until later years. I know there are other parents on here that have 3yo kids that are way beyond what is covered even in the third grade books in these subjects. These books might seem more like a simple story book that vaguely cover the subject matter.
One great thing about home schooling is that you can pick and choose what books fit your own kids the best. You can also start something and then decide to put it away for a year or so and get out later.
Hope this helps!