<p>If you have a choice in whether to change schools in junior year or senior year, I would encourage you to do that at the start of junior year. The application process in terms of guidance counselor assistance, teacher recommendations, ECs is much easier if you’re attending the school where you’re known.</p>
<p>Further junior year is critical in applications. Having a track record in the school from where you’ve applying gives you the best opportunity in terms of getting teachers to know you, and for gauging your grades come senior year. Also by restarting in junior year you’ll be better positioned to resume your ECs than if you move in senior year.</p>
<p>Finally, at a social level, changing high schools is very difficult for many students. Best is to get past the transition when you apply.</p>