Do what you said before circumstances invent a reason not to.

Circumstances always supply a reason. Something comes up, the priorities shift, and the reason is usually genuine, which is what makes it so effective at dissolving commitments. Acting early, before the reason has time to arrive, is the practical form of keeping your word.

When you agree to something, do the first piece immediately rather than at the deadline. Front-loading is not about discipline. It is about not giving circumstance the opportunity.