ETK ROP – Which bell?

I am doing ETK for the first time. I have finished the Program Minimum and moved on to ROP. I have been using a 16kg KB. This felt right for the first part of the program but have questions about the second part. I just finished week 1 of ROP and I find that I am able to do the clean and press ladders with no problem. The pullups wear me out by the end of the ladders but not the clean and presses. How much difficulty should I be having with the CPs at this early stage of part 2? Does it make sense to move up in weight? I have a 24 kg KB. Does it make sense to try that? Is that too much of a jump? Should I wait and see how I will respond to the heavier load of the upcoming weeks before making a move? The swing and snatch portions of the program still feel good with a 16. Is it OK to use to different weights? Many thanks for the advice.