Gift of Chaos Clarification

Quick question, is Gift of Chaos psychic power rolled for and resolved at the beginning of the sorcerers turn, as in before the movement phase the same as warptime?

It says "A psyker may use this power at the beginning of his turn" for GoC. For Warptime it says "power is used at the start of any 'player's' turn." I would assume GoC is used before the sorcerer does anything else.

This is of course open to interpretation. (rules as written vs rules as read kinda thing).