Why not stick to the sights?

Buy a shot timer, do your draws with a par time and slowly whittle your time down.

Dry fire draws without the use of sights is about pointless. How would you know where the would break? Sure you can improve your index after a while while conducting live fire, but you can see where the shots hit and adjust accordingly.

While competition related, buy Steve Anderson's dryfire book and a timer. With these tools, and some targets you can improve your quick draw.