3 seconds.....are you nuts ??

[TimTaylor]

Depends on when my closely guarded count started. If the offensive player was outside the paint when LGP was established & I stared my count a second or two before he dribbled into the paint, then I might make the 5 second call. Otherwise, if he was farting around in the paint for that long I've probably got a three second violation.

Please note the words "immediately" and "begins a try" in the rules sections you cited. If the defense is good enough to make the offensive player significantly hesitate or delay beginning the try for 3 seconds, the act is clearly no longer immediate. IMHO the intent of the rules cited is not to penalize good defense.