We investigate the infinite-temperature dynamics of the complex Sachdev-Ye-Kitaev model (SYK4) complemented with a single-particle hopping term (SYK2), leading to the chaos-to-integrable crossover of the many-body eigenstates. Due to the presence of the all-to-all connected SYK2 term, a nonequilibrium prethermal state emerges for a finite time window t_th∝2^(a/λ^2/5) that scales with the relative interaction strength λ, between the SYK terms before eventually exhibiting thermalization for all λ. The scaling of the plateau with λ is consistent with the many-body Fock-space structure of the time-evolved wave function. In the integrable limit, the wave function in the Fock space has a stretched exponential dependence on distance. On the contrary, in the SYK4 limit, it is distributed equally over the Fock-space points characterizing the ergodic phase at long times.