If their booking engine is to be believed (and during October it was good at predicting flights with a 777, and which were -300s and which were -200s, but less good with 787s) then the lunchtime flight will be a 787 from tomorrow until the 26th. The other flights in that period are 777s, split roughly 1/3 -200s and 2/3 -300s.
Out of interest do they qualify crews on both 777s and 787s, or will they have to position 787 crews in for tomorrow? If the latter it would suggest that they would need to know more than 24 hours in advance what will operate a flight, which with the planned 787s wasn't reflected in the booking engine on their website.