To continue -BUT the prop load is very small at low revs- because the prop is not really hooked into the air at low revs.
For example - imagine this -or try this.
make a pull test setup - (however).
Now run the engine up in 1000 rpm increments .
read the thrust at each 1000 rpm step.
What does the curve look like.
If you were hooked in water -the curve would - and here I am guessing, be quite different. No?yes?
My point is that as long as the carb is functioning as desired - the first 3000 rpm should come up fast.
The exception would be a very heavy prop.