I think that there's F on the 388 on every day that it's operating, which is (at present) from 1 December 2018 up to and including 28 March 2019. As far as I could see on a quick search, there are only two days in this period when QF127 is not the 388: it's a 744 on 29 and 30 January 2019. See https://www.ausbt.com.au/qantas-brin...s-to-hong-kong for more on the change this year.

(My personal interest lies in not having booked the 388 hoping for an F seat with J service - I would have been disappointed on being kicked out! And I'm surprised not to have seen this change mentioned already here.)