They could do it after season two so we could see them actually pursuing the people behind the Palmer poisoning (that was covered in the video game), but that would require bringing James Badge Dale back and I think I read that he hated his time on 24.
But they could easily set Jack's European adventures after season 4 where he's living under an alias and uncovers a threat, and the only people he can get help from are Tony, Michelle, Chloe and Palmer.
They will end up doing what they always do though with the movie taking place even more years into the future with wholesale cast changes that hurt rather than help.
Also, the concept of "prequel" with 24 isn't the same as with other franchises since the seasons are stand-alone and the show makes a lot of cast overhauls anyway.
But they could easily set Jack's European adventures after season 4 where he's living under an alias and uncovers a threat, and the only people he can get help from are Tony, Michelle, Chloe and Palmer.
They will end up doing what they always do though with the movie taking place even more years into the future with wholesale cast changes that hurt rather than help.
Also, the concept of "prequel" with 24 isn't the same as with other franchises since the seasons are stand-alone and the show makes a lot of cast overhauls anyway.