Where?

Only have JitD. Main rulebook says there are 5 tokens for Q1 and that the quests will list how many tokens to start with. However, I don't see any information in the quest book. Is it assumed that all quests start with 5 unless otherwise noted?

It's generally towards the end of the "Quest Goals" section. For example, in quest 1 it says "...You start with 5 conquest tokens. If you ever run out of conquest tokens, Narthak will have triumphed over you. Good luck."

Though all of the base game quests do, in fact, start with 5 conquest tokens.