It is hard to get definitive guidelines, but usually with this kind of coffees you want to have high extraction.
I dose 20 grams, my target is to extract around 50 grams of coffee.
I grind fine, I try to bit more careful with distribution. Without the digital PI, the PI can last 10-12 seconds.
But again, this is just very generic guideline, should give you good result, but probably you can start from there and tweak even more to find your own recipe.
Don't be afraid to grind finer with your Monolith Flat. I use my Monolith Max at setting as low as "1" on the grind set scale. This morning I used a light roasted Ethiopian Hambela at 1.2 grind set, 20 grams in and 36 out. PI time was 25 seconds and shot time starting when the first drop hit the cup was 48 seconds. Crema was full and very tasty.