You can use the 1:60 rule. If your turn radius is 1nm, then at 10 nm from the station, it would be 6 at 60nm, so call it 6 degrees.
For 2nm turn radius, allow twice as much, Einstein. And that is presuming you are tracking the arc, at 90 degrees to the oncoming radial. If you are at a 30 degree intercept, use half the lead angle.
Any other angle, pluck a number out of your fundamental orifice and have a go.
But try to keep your heading line between the fixed part of the CDI line and the moving part of the CDI.