When you cut a tree down, seal both ends of it as soon as possible. When you remove the bark, seal the wood underneath. Different types of trees check worse than others. I know osage checks a lot. I use wood glue for the ends because it is cheap, and spray shellac for the backs because it is easy to remove later. You need to get cutting. The sooner you get some wood dry, the sooner you can start making a bow. Best of luck.