The MIP Timing Detector that will be installed at the CMS experiment is a novel kind of detector which is going to assign times to charged particles with an unprecedented resolution of 30-60 ps. This will allow vertex reconstruction in 4D, an essential feature in order to perform pileup mitigation in the high vertex multiplicity environment which is going to characterize the High-Luminosity phase of the LHC. In this contribution, we explore the impact of the track path length resolution in the computation of the time-of-flight, which is a crucial factor that comes into play when computing precise time information at the vertex. In addition to that, a summary of the particle identification performance and its impact on the track time resolution will be reported. The results presented here provide the first estimate of the track path length resolution in CMS and reassure that its effect is subdominant when compared to the time resolution of the detector.