When do we have to use a reserve order in sentences?
1) in the questions, it's ok.
2) and now I've found one more exaple:
Hardly had we started when the car got a flat tyre.
No sooner had the game begun than it started raining.
From word order | newsobserver.com blogs
Speeches in this year's presidential campaign are awash in a rhetorical device called antimetabole, ... .
In this device, the speaker repeats words in successive clauses in reverse grammatical order, as in President Kennedy's "Ask not what your country can do for you; ask what you can do for your country."
Learn more here List of 18 Types of Subject/Verb Inversion