I highly recommend you to finish Flynn's route before TJ's because it'll completely change your perception of Flynn's character . Anyways you can start with Carl because his route has it's own lore apart from the other routes. Jenna's,however, has the best ending possible out of all.
TJ indeed should be the last, but many ppl did him first, including myself.
Since you've already finished Leo's route, it's best to start with Carl, then Flynn, then TJ and then Jenna because you should leave the best ending for last.