"I admit, I was not prepared for you samurai but i think in a fEW THOUSAND MORE YEARS I WILL BWAHAHAHA!…….. Ok Aku, gotta remember to actually prepare this time…"

15 seconds and 1 seizure inducing time portal later Jack arrives and finds that Aku once again forgot to prepare and/or underprepared because reasons. Honestly i've always headcanoned that Aku didn't know when or where Jack would show up and probably prepared for a few hundred years and then just let it all go to shit on him because he couldn't be assed to keep an annihilation squad prepared for thousands of years

Now imagine this, Aku creating a Time Portal… that sends him even Farther into the future.