My eldest took algebra when he was 9. The first semester was a challenge for him, but the ideas started sinking in during the second semester. My DD started algebra when she was 10, and we saw pretty much the same pattern --- after we switched her to a new book and started again.
Both are grade-skipped. Age gaps weren't much of an issue for my son at ages 9-11, but my daughter started feeling uncomfortable in 5th grade (a bit) and more in 6th and 7th. This year (8th) is better for her. Things started getting awkward for the eldest in 8th, but were much better by 10th.
The best advice I can give is to
tutor your daughter at home if her school uses a textbook produced by a mainstream publisher like Pearson or Prentice-Hall. US math textbooks are generally very bad, and are downright confusing starting at the algebra level. My eldest looked at the first algebra book my DD was using and...well, you can read my review
here. Look for "dog's dinner."
