I skipped mid 3rd to mid 4th. I wasn't really that much younger, but it was not good. It wasn't just that they were bigger or whatever, but at that age what you're going through is still pretty tightly coupled to your age. I didn't feel normalish until well into high school.
I don't recommend it. I recommend letting kids accelerate, but right now the consensus seems to be accelerate most people who need it at 9th grade, not 7th, and definitely not before. As with most of these things the consensus goes back and forth, but that squares with my lived experience.
I wonder if skipping in the middle of the year was particularly bad.
The recommendation you cite conflicts with Miraca Gross's recommendation for exceptionally gifted students, but they will be a minority of those who can grade skip.
I don't recommend it. I recommend letting kids accelerate, but right now the consensus seems to be accelerate most people who need it at 9th grade, not 7th, and definitely not before. As with most of these things the consensus goes back and forth, but that squares with my lived experience.