I am just finishing my first year with AP CSP and followed the order: U1, U2, ExplorePT, U3, U5 L1-10, CreatePT, giving full attention to U1, U2, and U3. Going to see what we can get through on U4 and the balance of U5 through the end of the school year, mainly the hands-on activities since there is way more Code Studio time needed than can be given in class time.
I found the full attention to U1, U2, and U3 necessary to carry the students that were completely new to these materials. Students with prior experience not so much but they still remained fully engaged and assimilated much more than they already knew.
With coding through U5L10, there are a couple of Code Studio activities (open design) that I think ended up taking students longer than should have because of project mis-management working alone; this slowed progress. E.G. the Mad Lib challenge (things got to look real strange in the block programming mode building the output string which seemed to be a mountain to grasp in itself).
I look forward to going through U4 as the subject matter is just as important as that in U1 and U2, IMHO.
Looking forward to next year, I realize that there has to be things that are merely summarized in class that also require at-home time to fullfill the Code Studio sequence.