Not a bad rep that mate. All I would say, is don't try and accelerate straight off the floor. Practice the first pull, and getting into the hang position. You don't need accelerate the bar significantly until the hang position. The purpose of the first pull is to ensure the bar is close, that your shoulders are directly over the bar, and that your hamstrings are stretched (that's the key reason). When you start to accelerate the bar and move as fast as possible in the transition phase, you will fully activate the stretch shortening cycle (SSC).
If you practice the first pull and make sure you slow that small part of the movement down slightly and get into that stretched position, you'll be surprised the force that the SSC will give you.
Don't have to go too heavy when training the 1st pull in isolation, but make sure its enough to challenge you. You wanna be holding it at hang for at least 2-3 seconds before you have to drop it.
Hope everything goes well mate.