Blessed Wine is being used at the end of turn even if casting it earlier would activate threshold. White cantrips are the backbone of white threshold (really, I'm writing the whole mechanic up ATM). If blessed wine is in a deck at all it's most likely there for that reason, and it doesn't have an actual purpose other than card draw (so it's more like a lousy card draw spell than an actual cantrip).

If it's possible, timing it to be cast at any point at all IF it would cause threshold to trigger would make it serve it's purpose much better. Prefferably before attacking / after blockers on offense, and before blockers on defense. The AI will currently use any cantrip as a combat trick this way, which is cool, but since other ones have actual purposes besides that one, it would be best if Blessed Wine got priority in that regard. You really can throw it out madly if it serves a purpose, unlike, say, Shelter.