Nose cone weight is used to increase the stability of rocket. By adding the weight to NC, it moves the CG (center of gravity) forward. You want a stability margin of at least 1.0 for most rockets. Many people prefer stability of 2.0 but there are exceptions to the rule. Also depends on rocket design.
Some folks don’t use sims and just go by trial and error. Most use Openrocket or Rock sim. They won’t tell you how much to add, you have to play with it and see how it effects the CG.
Based on the OPS questions, I'm not sure they will understand this answer...
For a rocket to be stable and fly correctly, the CG needs to be higher (closer to the nose cone) than the Center of Pressure (CP).
An unstable rocket will "sky write", flying erratically and possibly flying back into the people or crashing to the ground.
The CG is the balance point holding the rocket on its side fully prepped for flight, so with parachute/streamer, motor, etc.
The CP is the point where the aerodynamic forces from the side balance. Think of a weather vane and moving the pivot point until when the wind blows it doesn't move.
The CP can be moved down by making larger fins or having the fins swept back.
The CG can be moved forward by adding nose weight.
In terms of the stability margin mentioned above, the number refers to the rocket body diameter. A stability margin of 1 is the CG is forward of the CP by 1 body diameter. A margin of 2 would have the CG be 2 body diameters higher than the CP