Entschuligen Sie Mich, Meinen Damen und Herren, es war sieben und zwanzig jahre vorher das Ich habe Deutsch studiert, im Gymnasium.

<GIVING UP ON RECALLING HIGH SCHOOL GERMAN>
When does one move from the "Sie" Formal mode of address to the "du" mode? I have often wondered, in French and German, where there are formal and informal pronouns, when one moves from one to the other.

Wincing_Devil
I hope that Schrodinger guy put litter in here.