O − C diagram of synthetic transit times (T_0, s) of 100 yr (black circles) of dynamical simulations with TRADES computed using the Santerne et al. (2019) solution and including all planets. Highlighted are the two observing windows of ∼7.8 yr whose re-computed O − C (as described in Sect. 3.1) show the minimum (orange) TTV amplitude (A_TTV, min = 1.57 h) and the maximum (blue) TTV amplitude (A_TTV, max = 1.02 days).