If your doing 5/3/1 you do 5 sets of abs at the end of your leg day. Quit trying to change the program and just follow what the program says to do. 5/3/1 is probably one of the least complicated programs.
Workout day 1 - ohd press
Workout day 2 - sq or dl with abs
Day 3- cardio, sport specific training, etc
Workout day 3- bench
Workout day 4- sq or dl (whichever you didn't do on day 2) with abs
Day 6 - off day
Day 7 - cardio, sport specific training, hiit, off day, etc
The accessory work you do on each workout day depends on the template you choose to follow. Your doing BBB if I remember from your last thread. Those guys already told you what to do. Just follow the damn routine how it was written. Wendler is smarter than you, you know much less about weight lifting, programming, and the human body than Wendler. Follow 5/3/1 without revising it.