Triggers can trigger at any time, but wait to go on the stack until a player would get priority.

I cast while you control . What happens? After a creature spell resolves, a player receives priority. But it’s not as simple as that. Before priority can be received, first the game has to check for state-based actions (SBAs) – things like creatures with lethal damage dying, or +1/+1 and -1/-1 counters canceling each other […]

Read more.