Max did a much larger drop from +2 to +3. Though he often does start to move earlier. Without test data from +10 or +11 the cycle before, it's hard to tell if the lower +1 and +2 is part of an ongoing trend from the cycle before hand. Neko occasionally nadired at +13 and I even spotted it once at +15, so 3 hours after the following shot.
I have also seen other Lev cats that onset earlier, though can't remember which ones off the top of my head.
Once I learned how Neko used R, there were times when I'd use it late in the cycle if she was bouncing. Her onset was typically closer to +5, so late in the cycle there was still a lot of time for the BG to go up before the next shot took effect.