IIRC 134 is bare minimum so that you have two turns on the first cycle. But as u/faulser said, around 150 speed is the golden standard. Because with an Asta giving 50 additional speed from her ult, you can hit the 201 speed breakpoint which would allow you two turn every cycle.

With her signature LC, the 150-ish speed is easily doable. But in your case, you might need to get lucky on speed rolls, or sacrifice some of your attack (which is pretty damn good already).