You cast the copy of the card with cipher during the resolution of the triggered ability. Ignore timing restrictions based on the card's type.
Writ of Return
If you choose not to cast the copy, or you can't cast it (perhaps because there are no legal targets available), the copy will cease to exist the next time state-based actions are performed. You won't get a chance to cast the copy at a later time.
The spell with cipher is encoded on the creature as part of that spell's resolution, just after the spell's other effects. That card goes directly from the stack to exile. It never goes to the graveyard.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Kai Carpenter
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
