I’m not sure who the people behind ftdashoard.net are, but whoever they are, they should get a gold star for creating and maintaining an awesome site.
As mentioned in my trip report about new first class on British Airways, I used this site to track whether the new first class product was being used on the flight from LHR to SFO that I was going to take. As I was flying BA 285, I regularly checked the page specific to that route to see what kind of aircraft was used on that route for the day of the week I was flying. Leading up to my flight, that route had featured the new first class for each of the previous 4 Tuesdays, so I felt optimistic that my flight would also feature the new first class. Luckily, it did!
While past performance is no guarantee of future success, it’s a useful site to see if there are certain flights that are more likely to have the new first class. The overview page in particular has helpful aggregate statistics over the past two weeks (although I recommend searching for your airport code to find the relevant flights). For example, it appears that BA 282/283 to and from LAX is slightly more likely than BA 278/279 to and from LAX to feature the new first class, which might help you decide which of those flights to take if you have flexibility in your schedule.