Given that the indicative ATAR for the Bachelor of Applied Science (Speech Pathology) is 94, if you end up receiving an offer for this course in an upcoming round, such as February Round 3 or March Round 1 (both of which I believe would precede USyd's census date), then it should technically be possible for you to enrol in this degree prior to the census date. However, in the event that you (hopefully this will not be the case) don't receive an offer for your desired course in an upcoming round, how long you will need to wait before you can attempt a transfer to the Bachelor of Applied Science (Speech Pathology) may depend on the university that you choose to attend:
University of Technology Sydney:
If you choose to enrol in UTS's Bachelor of Advanced Science (Pre-Medicine), and subsequently transfer to your desired course at USyd, you may be able to attempt a transfer after only one semester. Students transferring to USyd from another university will be assessed on their ATAR or university results - whichever is higher. USyd states:
Your university results will only be considered if you have completed at least one year of full-time university study (or part-time equivalent).
This technically means that you should be able to attempt a transfer after one semester and be assessed on your ATAR. If you choose this path, you will have to either re-register with and apply through UAC or apply directly to USyd.
The University of Sydney:
If you choose to enrol in USyd's Bachelor of Science (Health), you will most likely need to complete one year of study. USyd states:
If your interests have changed, if you didn't meet the admission criteria or if you didn't get the required ATAR, you may decide to transfer after completing a year of study.
Additionally, an internal transfer means that you will be applying directly to USyd, as opposed to an application through UAC.
Additional information regarding transfers can be accessed using the following link:
I hope this helps!