Well lets say that you chose a smith incline press for your chest exercise for the day. And this is the first time trying dc training. So you decide to start with 225 lbs. You end up with 10 reps, 6 reps, and 3 reps, for 19 reps total. So you want to try and stay in the 11-15 rep range for that exercise. So you just put an up arrow in your logbook or any indicator that reminds you to up the weight next time.
Now the next time you have that same exercise you think 225 was pretty easy so you start at 235lbs. to try and find the right starting weight. Then lets use 2 scenarios.
1) you use 235 and get 6,3, and 2 reps for your rest pause set. Well that's 11 reps so you barely made it. At this point I would put an over arrow to let me know that I should use this weight again next time. I do this because I have left 4 reps on the table that should be mine. Plus the logbook forces me to know that I need at least 12 reps in 2 weeks when I attack this exercise again, or I will have to lose the exercise soon.
2) or you try 235 and you get 8,4,2 which is the range I like to stay in with any of the 11-15 rep exercises. At this point you got 14 reps and you can chase that one rep or decide to up the weight 5lbs or so. That's really up to you.
Anyway one main point in DC training is to not over-analyze anything so I don't want to be accused of it here,lol. But I remember starting out and trying to find the right weights while your also trying to remember to control the negatives and get it all to fit into a program where you were choosing the right exercises to fit the 2 way program and your recovery, so it was confusing at first.
Just remember to use that logbook and write down things you notice, how you feel with an exercise etc. and after a little while it will all become 2nd nature for you. And do yourself a favor and if you are going to try dc give it at least 6 months. Any program deserves that.