You are too early. PKP=the long distance train operator in PL only let is dear clients RES from 30 days before-though they state it should be longer for INTern. They always adapt the timings with a very few minutes-the basic pattern remains the same-except partly on 2/9- as the PL holidays end end the many seasonal to the sea or to the cool mountains cease to run.

BUT this does not affect yours: it is simply IMpossible to book these online-have to do in a german reisecenter (do not worry, trains are not fully booked weeks ahead) and even though it should in theory be possible to RES for Kr->Pr-but depends on day or night-train: many reports in this forum in the end conclude it simply will not go.

AND; I now again have to write this but this is all in a getting bigger by the day overveiw of seewulf on hottodoit-IF possible-on yourown and cheaper too as via app. Plus that in fact also the pretty long overveiw-but nicely cut up in countries from EU/IR itself also clearly states what is not possible online.