|Based on a multi-time-dependent generalization of the P function, the so-called P functional, a technique is developed to reveal nonclassicality with respect to multiple points in time. In this multi-time scenario novel eﬀects occur, which are not present in the single-time case. Furthermore the detuned nonlinear Jaynes-Cummings model is considered. It is shown that its dynamics can be solved exactly if the Hilbert space is extended. It turns out that the model is especially suitable to study non-equal-time commutators of the corresponding Hamiltonian.