>>717798945 >>717798287
You can Change in neutral 18 frames after the call, as soon as the character lands on the ground but before they attack.
Doing the assist raw, when you can change varies depending on the slot and if it's hit or block.
Shooters can change during active frames, allowing them to be the ones to start and pick up the combo.
Vertical and Assault appear to have to wait after the recovery frames regardless, so the current leader has to be the one to follow-up.
Aerial assists are all like Shooters and can change on hit.
During combos, all assists have to wait after recovery, requiring the leader to fill the gap with at least one or two hits before the change.