I was going to hold off on clearing that up, but quickly:

No, it's a matter of chronological confusion on Selena's part (probably from reading fast). She originally wrote, "I don't think it occured to Katte this early," but then the full translation (thank you!) says:

When Katte was transported to Küstrin

Now, that was November 3. By then, Katte knew he was on his way to his execution, had written his pleas for pardon in vain, and all but the faintest shred of hope was lost. This is the point at which he's giving away all his books. :(