Nebensatz zuerst: Verb, Verb

When the time clause comes first, the whole clause takes position 1. The main-clause verb follows straight after the comma:

• Als ich ankam, regnete es.
• Wenn ich Zeit habe, lese ich.

Verb, comma, verb — that’s the sound of a correct sentence. The trap: the subject first after the comma (“…, es regnete”).