First year linguistics has five main topics, split between the two courses. 1A03 focuses on phonetics, phonology, and morphology, while 1AA3 focuses on syntax and semantics. With what I can recall when I took the courses, there was hardly an overlap between 1A03 and 1AA3 so I think you should be fine taking 1AA3 before 1A03!
And by scheduling 1AA3 first, they would know most students (at least first years) would not have had the chance to take 1A03 yet so I'm sure the course would be adjusted to accommodate for that if it needs to be
