Even with having a Backbend KO and a BWO, 16 days or less is a short time to learn how to properly preform a BHS.
Learning new skills is not something that should be rushed. I follow the philosophy "Perfection before Progression," meaning that you should not move on to learning a higher level skill until the skill you are currently working on has been completely mastered. I know this might not get you the quickest results in the beginning, but your tumbling will be stronger for it.
So, don't rush yourself and learn your BHS correctly. You will be glad you did.