You can choose a blessing aligned with your purposes, with your god/dess, with your practices, or with anything else you like. You could write your own or find one online that goes with what you want.
The journal which I use to record my experiences truthfully has no blessing on it. It simply starts out with my full name and my spiritual name, and then on the following pages goes into my experiences, when and how I gained my spiritual name and what it means. You don't necessarily need a blessing on it.