If you are not 5 minutes early you are late.

It is always better to arrive 15 minutes early, because 15 minutes early is on time.

As I have been taught, especially in the service (U.S. Army), it is always a good idea to be no more than 10 to 15 minutes early for an interview. It does give you time to calm yourself, look over your resume and look around a bit from where you sit.

If you on time you're late, if you're early you're on time. Check out my book, American Holocaust" Information Society by Larry Jones on Amazon and Kindle.

Arrive early for interview, your job "if employed". My father, was a good coach by saying "be punctual about everything related to work".

show up to a interview #20 minutes earlier

I try to arrive 10 to 15 minutes early

For me, half an hour. This helps me to be prepare and relaxed before my interviews. On the other hand, it shows your prospective employers your commitment of being on time, if you're employed.

it's better 20 minutes early, more than 1 hr is too much

It's best if you arrive on time. This way you won't appear to be over eager. If you get there early wait in the parking lot until just a few minutes before your scheduled appointment