Rule reminder
In extended contexts, the correct periphrasis depends on: the temporal aspect (start, ongoing, end, imminent), the register (formal/informal), and the narrative relationship between events. Pay attention to time words (improvvisamente, gradualmente, sempre, da anni, stava per, appena) which signal which periphrasis is needed.
'Il medico ___ di spiegare la diagnosi quando il paziente è svenuto.' (had just finished explaining when… — completion before event) Best?