If an offensive player commits a lane violation before the shot, do you go ahead and blow the whistle? Or, do you wait until after the shot attempt?

Blow it dead immediately.

I disagree - if it is not by the shooter, you wait to see if the shot is successful. If the shot goes in, there is no advantage by the player breaking early, therefore no violation. At least this is the FIBA interpretation.

NFHS rules. A lane violation by the shooting team causes the ball to become dead immediately. Blow the whistle and move on.

Hold the whistle on a violation by the non-shooting team. If the shot goes in, ignore the violation. If it misses, blow the whistle and award the substitute free throw.