Take the summer course if it is needed to get into Physics C next year. Our school teaches APCalc AB and AP calc BC as separate years(AB is a mandatory prereq, so BC only covers second semester college calc). Kids in Calc AB are allowed to take Phys C concurrently, but they have some extra summer work on calculus–not tons. D21 asked to have the extra work despite finishing AB, because it was Covid Spring 2020 and they didn’t quite finish AB curriculum(and math isn’t her favorite). It was an introduction to basic calculus, so a review for her. The course is much harder for the concurrent-ABCalc group, but the teacher dives deep into complex problems beyond the text and has a very high 4/5 rate on the exam , so it works. Both of mine took Phys C concurrently with BC(so after AB calc) and found/finding it hard but doable, not difficult to pass the AP/get credit.