Another way to go, if you do another playline: when you arrive at the Mill, don’t go and talk to Lord Radzig at all until you feel you’ve explored all you want. There is no question that, when you wake up at the Mill, you are free to do whatever you like for as long as you like, and it is only once you enter the chamber with Lord Radzig that the freedom is curtailed.
I played for something like 200 hours (a normal play line for 120 up to about level 14 and then 80 hours in a hardcore up to about Level 12 or so) before going to talk to Lord Radzig. There is PLENTY to do out there in Bohemia without talking to Lord Radzig, and honestly it is a lot of fun for a long time.