Mmm, I don't think it makes a significant difference, but the ATAR estimates for each subject changes a bit every year anyway depending on how everyone performs..
Idunno, I refreshed the page every 1 minute on my pc last year, and then when the username/pw popped up, I looked at the clock and it was around 5:55am, I was like, "holy shit, it's before 6am... this is the moment :/ ..."