OP this is a unique year for the county's sixth grade band and orchestra programs. Pre-pandemic, students would come to sixth grade band and orchestra with two years of school instrumental music lessons under their belt. They understood the basics. Some came with private lesson experience and others (especially in wealthier parts of the county) started private lessons in 6th grade. The classes became increasingly challenging each year.
This year, directors are taking more sixth grade beginners than ever, becuase pf the attrition rate from distance learning and last year. The best middle school directors are quickly bringing the students up to speed. It's a mammoth task and it will take a couple years to work out.
Some middle schools allow students with significant experience to "play up" a year. Your DD might be a candidate for a schedule change to the 7th grade orchestra. Otherwise, ask the director about the audition requirements and dates for all-county middle school orchestra. Also, there is a county-run solo judging event that your DD may want to enter.
https://www.montgomeryschoolsmd.org/curriculum/finearts/instrumental.aspx