In 100 hurdles what measurements should I have for my blocks?

I'm in track and we have a meet tomorrow. I was gone when we learned how to do blocks because we have to start off of them. I understand how to do them, I just don't know what my measurements should be. I put my right foot forward and left back. I'm 5ft 5. My torso is about 2.5 feet and my legs are about 3. So what numbers should I be at? Thanks for the help!|||You should try and see what works for you. I also do hurdles and you just to see what is comfortable to you.