48 hours it means that guessing already closed since 31 Aug 2015
So if you bet more than 3 Aug 2015, your prediction will be invalid (CMIIW)
48 hours prior to the deadline, the deadline is 5th October, that makes 3rd October to me. So since its 25th September today, entries are still open.
"Prior" means before, not after. Since it can't close before the thread was made, it's obviously before the deadline.
"This" being the deadline, not the time the thread was made.
Funny thing is, with your closing date, even MICRO would've missed it:
Date joined: 10th August 2014
Price that I am guessing: 231.29