Not the answer you want, but ECID. Some kitties seem to let you know after only a couple of days. Others (Copper is a good example), seem to take 4-5 days before settling into a new dose. I think what you look for is for a pattern to emerge and repeat three or four times before you can reach a conclusion about whether to drop, hold, or raise.
Also, try to keep this in mind. Sam has no idea he's "sick". He just knows some days are better than others. What he does realize is that he's getting a lot more attention and love nowadays than he's used to. And once he associates the pokes and needles with "hey, I'm having much better days with all these pokes and needles", he'll learn to love it. It took Bob a while, but he learned that the treatment meant treats and feeling better, and he'd get to the "test spot" before I did lots of times. Even now, 8 months after his last shot, he runs when he hears the test case zipper or the meter go "beep". Only hears it one a month, but he remembers...
Carl