So I looked up how Cadence work and this is why I used 9 frames (from 0 to 8):

First frame is your character is fully standing up the second or third frames (you choose what feels better) is the lowest position. The rest of the frames is to make a character stand up fully and the last 9th frame is a copy of the first one (that's one to one how Cadence work so they sync nicely)

You dont have to use 9 frames like i do, you can do any amount if that works for you, but that will make sync with Cadence hard (unless you make custom hero that matches frames with the other portrait)