conjunction
as soon as, once
B1
'sobald' is a subordinating conjunction meaning 'as soon as' or 'once'. It introduces a subordinate clause and sends the finite verb to the end in German. Common for temporal sequences: action A happens, then B 'as soon as' A. Use comma to separate clauses; not a preposition.
Examples
Sobald die Gäste ankamen, begann das Konzert, obwohl das Wetter schlecht blieb.
As soon as the guests arrived, the concert began, although the weather remained bad.
Sobald er angekommen war, begann die Besprechung.
Once he had arrived, the meeting began.
Ruf mich an, sobald du zuhause bist.
Call me as soon as you get home.
Details
Mnemonics
Picture a clock with the words 'so soon' flashing when the time arrives.
Sounds like 'so bald' — think 'very soon' (bald in German means 'soon').
Notes
A subordinating conjunction that introduces a time clause; it sends the conjugated verb to the end of the subordinate clause.