I noticed you've been watching a bit of mind pump stuff, they often go recommend next to no cardio unless that's what you really love doing. They more recommend walking or if there's a sport you love playing get your cardio through that.
In that case, 3x a week should be enough if you can get away with nothing. I do like it and since my resistance exercises have me resting 1-2 minutes between sets, some hard conditioning on the side wouldn't hurt me.