Witcher 3 DLCs before or after endgame quest?

I've de-cursed the elvan sage/Uma, and on the phase where it's having me go around and check in with friendlies to gather strength before getting Ciri and drawing the hunt.

Without spoilers, is there any reason to save the Hearts of Stone and Blood and Wine quests? Or is there a reason to do them now? Or does it not really matter? So far the only factor I'm aware of is that Witcher gear set bonuses apparently only kick in after getting the highest-level upgrade diagrams from Toussaint.