From a time-dependent perspective, the direct investigation of the excimer's dynamics has been likely hampered by the size of the system, which may blow up the costs of standard protocols, and by the very long fluorescence lifetime, which raises the point of a statistically meaningful sampling of the conformational space. Moreover, the issue of identifying an appropriate initial configuration must be addressed preliminarily: this becomes particularly challenging when considering the widely accepted excimer formation mechanism involving free diffusion and collisions among monomers. It was only recently that surface hopping (SH) has been applied to probe the gas phase dynamics of the excimers of pyrene (TD-DFTB), 36 benzene (ADC(2)), and tetracene (using a combination of TD-DFTB and semi-empirical CISD methods). For pyrene, mixed quantum-classical trajectories were propagated for relatively short timescales (2 ps), sampling the initial conditions from a ground-state optimized configuration. A fast relaxation of the excimer towards a perfectly stacked conformation is observed, dumping the residual displacements inherited from the initially sampled ground-state geometries. However, the mechanism of fluorescence emission for the pyrene excimer, although essential to grasp a deeper understanding of this peculiar species, has not received equal attention. Remarkably, the well-known eclipsed conformation is characterized by an almost negligible oscillator strength for the S1→S0 transition. Although the coexistence of different local minima in the multidimensional potential energy surface (PES) of the pyrene excimer has been recognized in some of the studies mentioned above, its possible relevance to fluorescent behavior has, to the best of our knowledge, been explicitly suggested by only a few of them. To address the role of conformational dynamics in pyrene excimer fluorescence, we conducted a comprehensive characterization of the first excited-state potential energy surface (PES). We began by simulating the excimer formation through a diffusive process, where an excited-state pyrene encounters a ground-state counterpart. This approach enabled us to capture the stochastic nature of excimer formation.