Rising with back parallel to ground

[WiscoVaulter]

I recently had a meet in which i PR'd. I recorded every jump I took with a bar and I compared it so tome elite status vaulters. When I vault, I rock back and then I 'stay'in that position with my back parallel to the ground. When I watch elite vaulters, their backs are only parallel to the ground for a split second. Is this a problem with the swing? Is it me just hesitating to finish the jump. I also have a problem with not turning early enough. Some videos of the meet are below, they are my last two makes and my final miss. Any responses are welcome.
Thanks

https://www.youtube.com/watch?v=n5GaUhbg12Q

http://www.youtube.com/watch?v=lSfl3UDn ... e=youtu.be

http://www.youtube.com/watch?v=xoCHvPWn ... e=youtu.be