Most (all?) modern postmils believe that the binding of Satan started with the Cross. But a realised or inaugurated eschatology does not mean that there will not be the great progress that postmils posit from Scripture.
Eschatology was realised/inaugurated in the First Century, at least by Pentecost and the destruction of the Temple in 70 A.D. But look at the great progress that has been made since then.