it's recommended for the fastest kids to take compacted classes. Pushing 7/8/9th grade in two junior years. Or 9/10/11th (Algebra I, Geometry, Algebra II) in two years. The official documents from my states does not recommend compaction before 7th grade.
I think it is easier to compact before Algebra I. If not, even MG kids willl be bored stiff in elementary years. The new common core dig deeper in Algebra 1, Geometry, etc.. and I may not want to compact those. I would compact prealgebra and start Algebra I at 7th grade for Gifted kids. Perhaps, a few PG kids may join that class in 6th grade. Besides, there aren't enough students (typical school district) who can handle Algebra I, II and Geometry in 2 years in a typical school setting (with lots of homework).
Some kids in the neighborhood did this; they study one of core classes (Algebra II or Geometry) on their own, take the test and get the credit. It may have been attributed by the desire to skip the teacher who teaches Algebra II in HS(bad teaching and >1 hr homework per day).
