@SlalomSteve I think the most traditional way of progressing is to not move on until you can run the pass back to back. If 32 mph still feels unattainable I would shoot for something more in the middle. Bump up to 30.5 or 31. I know some people who like to take 0.2 mph steps.
I have used what I call the stairs method in early season. So for me it looks like -28, -32, -35, -35, -32, and -28. Builds consistency. I wouldn't be afraid to try and drop back and do 28 30 30 32 30 28.
One thing that I think is somewhat overlooked but very important is to always end on a clean complete pass. We are building muscle memory and the last thing you want to do is learn bad habits. Even if it means the last pass is 28 run the last one early and wide.