You will probably get more advice if you post this in the hacking section. If you did not have the device back when 4.3.3 was the current firmware available in iTunes and saved the blobs then there is no way to downgrade the firmware. Also, you cannot use another persons blobs as they are unique to each device. So if you just got this unit and it already had 4.3.5 on it (or you upgraded it to 4.3.5) then you will not be able to jailbreak it. Your only hope is that the devs are able to find an exploit in iOS 5 when it comes out.