I will guarantee you this: all your cardio work will mean **** all the moment you step in a BJJ class. You will gas regardless of how strong the ticker pumps oxygen through your system. You will gas in the first twenty minutes. You will gas your first roll and you will gas for the next month or so. The reason? Because there is a difference between having awesome cardio and having awesome cardio while you have 100kg on your chest restricting your breathing for extended lengths of time, while you panic and your body goes into fight or flight mode, but being unable to flee you start wildly swinging your arms, bucking like you were on the Pro Bull Riding circuit, except you're the bull and there is no minimum or maximum time the rider must stay on for, except at his or the instructors discretion. Your breathing will be shallow, fast and ragged. You will end every roll panting like a puppy that just discovered it loves chasing cars before collapsing in agony wondering how, with all the exercises you did in the lead up, exactly HOW have you found several other muscles you didn't know were there, as well as why your joints feel like someone has injected a balloon that is slowly inflating.
To reinforce Miyagi's point, the best way to get fit for jiu jitsu is to do jiu jitsu. It's a completely different cardio than anything in other martial arts.
BJJ makes other martial arts' cardio seem like a lazy stroll through a rainforest while breathing through a gas mask connected to an oxygen tank that someone else is carrying. At first. There's a caveat.
Also, stop paying for inferior products.
This is an unpaid advertisement for BJJ, spoken by battlefields for the JUST FUCKING DO BJJ AND STOP PRETENDING YOU'LL EVER BE "FIT" ENOUGH TO PARTY party.
Train what you want to train. Bullshido will still be here.
BJJ, like other grappling on the ground martial arts, is an anaerobically intense sport. It is hard to train for this outside of the sport because like battlefields stated, it's an exercise that pits all your muscles against your opponents.
A few years ago everyone said HIIT training is one of the better ways to prepare and to train for grappling without the grappling.
I'm going to say that sprints and the followed by the grappling circuit will give you the best results as far as s&c for bjj. Though really you'll be more tired from lack of technique.