Thanks in advance
Immediately, if you have the intention! Have to make money.
And you have it right away.
Who does not intend to earn money
People who make it out of hobby.
I earn money as a hobby
Yes, that will be a trade then.
Look here.
https://www.gewerbeanmeldung.de/wann-muss-man-gewerbe-anmelden
Whether you make profit or loss, the trade license does not care. You are obliged according to § 14 GewO to announce your commercial activity at the same time as the beginning. And it starts with the switching of advertising.
The point of the business advertisement is that the office (in its supervisory role) knows WHO WHAT DOES WHAT…