Nanolaser modelling still presents difficulties stemming from the complexity of the physical problem and lacking a simple and efficient way of predicting the temporal evolution of the laser field. The application of a Stochastic Simulator to the case of a large-β laser shows how this new approach can deliver precious information on the relative fraction of stimulated (and spontaneous) photons in the output, together with the fluctuations intrinsic to the stochasticity of the physical processes (emission by atoms and transmission by the cavity). A brief discussion of the open problems in nanolaser modelling and characterization is offered.