Oof, yeah, waiting is the worst!
Usually, when I am in that situation, I will paint the minions because (in my mind) they can get away with the less quality paint job. But in the case of Titania's box, her minions are so characterful that the lower "minion quality" is a disservice to them! But if you work on them now, while the queue is empty, it is a few less things to paint later