You can start working on your personal statement now. It's not a response to any question.
I would to go to professors, PI, or dentists, in person, and ask if they could write you a strong LOR. When AADSAS opens, there is a section where you can enter the recommenders' email addresses. AADSAS will send an email to the LOR writers and they will each upload an online copy to AADSAS (all the instructions are in that email that AADSAS sends to LOR writers).
After you do all this, you can then worry about secondary/supplementary applications that some schools send to some qualified or all applicants. Search the web to see if the school of interest even has a secondary and if they do what questions they ask on it. The secondary/supplementary is where you write in response to an open-ended question. There is also a word limit.