I haven't used the CJ, personally, just the AJ, but I see no reason you couldn't lay CJ down on top.
However, the AJ is a very good LSP all on it's own. The CJ is mainly for people that like the different look of a carnauba product. I find AJ to be very easy to use, as long as you go thin (like just about everything). I use a MF covered foam pad to apply and spread thinly, and a MF cloth to wipe up any remaining residue... works great, looks great, and lasts.
Did you also order any prime? Or do you have AIO or anything similar as a final prep before the AJ? I haven't tried AJ without Prime, personally, but I would imagine it wouldn't last quite as long, because the prime does leave behind some protection, too.
