HI @ebreard
This is possible but way complex than it should be.
If the timesteps progression is linear (eg: 0.1, 0.2, 0.3), you can use TemporalShiftScale to shift your timesteps and then PythonCalculator to compare between timesteps and do the computation.
If not, then it can only be done one timestep at a time, using ForceTime or TemporalArrayOperator.
Hth,