Sweet spot for intensity

Hi!
I just started jelqing and am experiencing mild ED right now. I can get as hard as normal, but the erection subsides a little faster than usual and getting it up without “material” takes a lot longer. I don’t do stretches. I am pausing PE, until I get to my normal levels again.

I want to dial down the intensity, but it’s hard to know, how to find the sweet spot, or to know, where I am on the intensity scale. I jelq at roughly 70-80% erection level I think, my member is full, and barely not rigid.
I used the search function, but I could not find satisfactory answers.

How do I know, I am in the low, middle or high* intensity level? As in: How do I know, I am so low on the intensity, that I still make progress and put as little strain as possible on my member? Do I have to feel blood rush through my fingers during a stroke, or is (light) caressing with hardly any or no expansion also effective in the beginning?

Thanks for any answers or links!

*High is easy, just hard squeezes.