Assume Craig's CCZ factory and assume you're CCZ-generation limited (i.e. small number of factories).
Wall_time = n_tof * n_cycles * cycle_time
n_cycles = 5.5 * factory_distance
Assume factory_distance of 31 and cycle time of 1us
Wall_time = n_tof * 5.5 * 31 * 1us
Wall_time ~ 1.7e-4 s * n_tof = 2e-9 days * n_tof