Not quite true.....
The details above (posted by Silberfuchs/Mizzy) have changed....that was the plan but it is not anymore!
There are going to be SOs crossed trained from the 744 but they are still primarily 744 SOs and do all their SO simulator modules in the 744.
BUT.....
There are also new joiners coming direct to the 777 as SOs. ie: they are joining as 777 SOs.
They will cross qualify onto the 774 after 4-6mths but they will remain primarily 777 SOs. ie: they will do their SO simulator modules on the 777.
Obviously for ease of JFO upgrade, these SOs will upgrade into the right hand seat of the 777 after approx 3yrs.
For new joiners, told they are going to the 777, this is the current plan.