Having a goal is entirely the wrong way to approach tai chi. Just coming along and doing the lesson, then working on whatever little section you're at, is a much better approach.

Having goals leads to frustration if you don't achieve them quickly. When you abandon goals and instead just work on having a process, you make much more solid progress. Approaching tai chi as a process, means you learn to work in the moment, doing what you're doing, and you learn to relax as part of that process.

There's a famous martial arts story, where the student asks the master how long until he learns the art. "10 years" is the answer. "But what if I work hard every day, all day". "In that case,  20 years". This is so true - people who  are goal oriented can't  learn how to relax, and relaxation is the key to being able to improve at tai chi.

I see this in my own students too. Those ones who  just go along with the flow, do what they're doing, working on where they're at, learn to relax and start to internalise tai chi as part of their lives. Those ones who are desperate to achieve some goal can't relax and stay at the robotic stage, even after they've learned  all the way through the form. The relaxers then overtake them, even if they've taken far longer to learn through the form.

Abandoning the desperate desire to achieve a goal and instead just working on what your instructor is showing you, will really help you relax and make progress. Try it and see!