I have always felt that the preparation for high school is too little and too late, both in terms of academics and of advance planning. Especially in a system where APs have prerequisites, kids and parents need to know that so they can plan coursework accordingly.
All of the schools my kids attended waited until 8th grade - usually spring -to address the HS plan. Parents need to know the critical nature of the usual sixth grade test, which determines who gets on the top math path, which will also determine eligibility for AP Physics BC (calculus is a co-requisite). There is just far too much mush and wasted time; kids without aware parents who are able to supplement are hosed before they hit 7th grade.
BTW, I've found it fairly common for a shared MS-HS campus, so taking some classes at the HS may be possible. Also community colleges, universitites etc - whatever is available.