@Booajo, one data point: my S14, who was a strong math student in HS, did the track your D is proposing. He took AP credit for 1 & 2 (5 on calc BC test) and then took non honors calc 3. He did well and did not struggle too much. He took BC as a junior in HS and calc 3 as 1st semester sophomore at Pitt, so there was an 18 month gap in between.