Question about cuttings

My neighbour gave me a cutting off her thornless blackberry plant and I'm not really sure what to do with it, I've trimmed it down to 6/7 inches and left a few leaves on it, dipped it in rooting gel and put it in a propagator. On the cutting there's a flower which has opened up today, would it be best to cut the flower off? Any info would be great thanks

 

I would cut the flower off so the cutting puts its energy into putting out roots.