Rhetoric, in this course, is the art of finding and ordering the available means of persuasion in speech — ordered to what is true and good, not just to persuading. In a certain sense, of course, rhetoric and the use of it do not wait until we have mastered the art of grammar; this is true simply because we speak and read and persuade others all the time without having mastered grammar.
Nevertheless, rhetoric does still presuppose grammar and logic, even if only in a rudimentary way. A speaker who cannot form a statement or follow an inference has nothing yet to offer a hearer except his own character and personal influence.
Besides, training our speech is not a later veneer on a self that we have already completed. Training our speech is a key part of how each of us becomes able to give meaning to others and to provide meaningful perspectives on decisions or open questions, which is the goal after all.
If you are searching primarily to train yourself for self-expression and finding your mature voice, then the later sections here will allow you to take a look at rhetoric sooner than the default order. That is not because self-expression and finding your voice are first. It is because part of knowing how best to take a course of study is knowing where that study is going and where it ends; so, before we begin, we look down the whole course of studies and skills of the trivium. But then you will be sent back to the best beginning, which is grammar and then logic. The foundation is the same: words first, because teaching and learning are already always done in speech.
The next sections begin from ordinary experiences of being misunderstood and of making a promise. Think of this, if you are still focused on finding a voice for self-expression, as a way of training and honing and refining your capacity for self-expression.
Continue to Why we begin with words.