Tain respawn time?

[syztem]

Accidentally didnt turn into tain quick enough(was MQing) and he got killed by an orc or some shit. Everything I read says 30 minutes or 3 hours for respawn, which is it? Also people say not to give him the elixir immediately on spawn? does that mean i need to trigger him with "i will help" then turn it in and let him get squashed? or to be on the safe side do i need to kill ghrek and his minions all over again?