If you are pressing 20 @ 90 pounds on your 3 working set there is something seriously wrong with your initial 1RM estimate.
Assuming your 1RM is closer to 150 then
150 * .9 = 135 is your estimated training max.
135 * .85 = 115 for you 3rd working set of wave 1.
Although guessing your 1RM from a 20 rep set is kind of hinky. You need to establish what your 1RM's are.