As a "gold" I got upgrades on ca. 50 - 60% of my flights.

At my home airport "Düsseldorf" the upgrade happens at check in.
I am always very early at check in, so the upgrade is in the system when they start the check in.

In all other airports the upgrade happens at the bording gate, where they write a new seat number on my bording card.

I never asked for an upgrade, they do not know me personaly, but I often travel on busy routes.