Direct answer
Objectives follow journal display order. Some depend on your choices; follow the active objective in the game.
Result
Traveling via Geralt's most beloved means of transport, teleportation, Yennefer reached Kaer Morhen first - and immediately started bossing everyone around. Not only did she divvy out chores to the witchers like a schoolmarm whipping lazy pupils into order, she also refused to reveal any details of her plans. Though Geralt was not exactly charmed by this behavior, he knew he had to help her - for Ciri's sake.
