# When does a readied action trigger on “when the enemy moves”? [duplicate]

When my trigger is "when the enemy moves", when does the readied action trigger, after they move 5 ft, or after finished moving to their intended location?

I'm asking because I might want to use a pike to deliver the spell. If it triggers after the target move 5 ft, then I can still attack them and complete the spell. If it waits until the target completes their movement, then they might have leave the 10 ft reach of pike, and thus waste my spell.