The general advice in the community is that if are meeting the “exit criteria” for a Stage (generally on the last page of the chapter, you should start the practices for the next Stage.

It can feel wrong, like you are “not done”, “it’s too early” to progress this way, but it is, in fact, the best way. The Stages are not so strictly progressive that mastery at one Stage precludes working on the next. To use the gym metaphor, if you are lifting at one weight, when do you move up? If you delay moving up until lifting at one weight is so easy that it does nothing, you’ve wasted gym time. You move up when the current weight is doable but still requires work, and the next weight is a challenge but still doable.