to my knowlage, we will be gettin events like increased rate of attack hime, or tricky hime, but idk if its increased chance of gettin SSR in general, or just increased "weight" of certain hime types within that 3% bracket. i would assume its the latter. as for when to use jewels... its up to you honestly, but i would avoid aiming for SSR, since that is unrealistic. i would wait for an SR tier hime that you want to get released and then try your luck on gettin her.