What build do you currently have on your Cybook? You can check by selecting the 3 button from the bottom on the left handside of the Cybook, then select Advanced > About.
Under Boo Reader, you'll find the build. If you already have Build 538, then you do not need to update your firmware.
I posted the procedure that Bookeen sent me in regards to getting the time set on the Cybook in this thread along with a file that Bookeen sent me. That file is fairly simple, but you may need to contact Bookeen and get an updated file.
https://www.mobileread.com/forums/showthread.php?t=21988