Sorry, elderly neighbour locked herself out of her house. Back now.
Max likes to plummet between +2 and +3. You are right that you don't want the onset and R peak at the same time. Next R experiment I'd try at +11 if over 300 and clearly rising. At some point that might even shift to +10. But try the +11 first.
Looking at this cycle, and comparing to the last time you used R, both were to cap a bounce. But the first time he was only to pinks at preshot time, and kept going on up, so R helped slow that down. It seems when Max really rises a lot (like he also did on the 2/22), he does come down on his own fairly quickly, but not always.

Looking at 2/18 or 3/08 PM, he shot up over 400 at PMPS, but was very gentle coming down. That would have been a good cycle for R. Now we need to, as DH called it "read the tea leaves" of the spreadsheet, and see if we can see patterns when it's not a good idea to use R, and when it is. Basically, what patterns lead to higher numbers that don't plummet right away.
I'll gaze at Max's SS a bit more, and see if anything leaps out.
I wouldn't shoot R at the end of this PM cycle. You can get into a viscous cycle of shooting R, causing bounce, shooting R. Let's let it settle down first and wait for the following opportunity.