Using him at the moment, he works fine for me. He doesn't fire late, he just fires same as normal prompt mystery, if you have him move 1 with best gear he will go before anyone else.

i am talking about the y+1 mystery that gives an extra attack to curse mark ninja. if i use it in round 1, it should trigger in round 2 before the pos 1 mysteries fire. it does not

Why would you think it work different from +2, it's worded the same way as +2. No other mystery in game does what you are sayin as well, only some passive skills.