How does graduating a semester/term earlier affect your chances? An early-grad at my school told me it could negatively impact admission officers' view of you.
It depends on what your college plans are and where you intend on applying to.
There are many different types of college applicants.
Some HS students plan to matriculate into community college as soon as they graduate. If you are someone like that, graduating early will not matter.
Some HS students plan to apply to non-competitive or somewhat competitive public universities, if you are that type, you should be alright.
If however, you plan to apply to very competitive or top schools, you have to show a great reason for leaving HS early because most of the other applicants are using every day of HS to show the best possible academic and EC record they can to their college admissions officer.
Just because you have fulfilled the minimum graduation requirements is it a good idea to leave HS? Some would argue not.
The best students in America, often graduate with a transcript that is 50%+ thicker than the minimum standards (36 credits vs 21.5 credits for instance)
Why would someone want to take 10-15 AP classes and strive to get A's and score 4s and 5s on the tests when none are required?
Why would someone want to take dual enrollment classes at a community college concurrently during HS?
Why would someone want to take online college classes during summer breaks while attending HS?
Simply because it sets them apart from the competition for the fewer and fewer spots at top universities.
By this argument, the same kids are the ones that take the ACT or SAT 2-4 times often using Summer/Winter/Spring break to cram so they can get 95%-99% scores to set them apart even when 400 of the top colleges are all test-optional.
For these types of students who are well represented on CollegeVine, finishing all four years of high school is not an option but an opportunity to show admissions officers the very best version of themselves. For them, there is really no "senior slump", more like a "senior slouch" where they might forgo some AP tests that have nothing to do with their intended major in college or readjust which ones they are taking so they only work on the ones they can get 4s and 5s on.
The exception to this is if you are using your GAP semester to do something intellectually pertinent to your narrative. If you get an internship for four to six months at a BioTech lab because you want that experience of research before you start your Pre-med track, and your academic transcript is already the very best it can be, then go for it. However, if you are going to use it to work at McDonald's to save up for a car or car parts, well that's not very convincing.
Good luck with your decision.