What do you put on the first page of a new notebook? A title, an index, or just whatever you're writing that day? That first page always seems to get treated differently from the rest of the book, even though it's just another page.
I'd keep it simple: a brief label and start date on the first page. I'd add an index only if I expected to look up entries later; for a straightforward journal, I'd just start writing there.
I'd use the first page to note what belongs in the notebook and what needs transferring to my ring planner. It gives the page a job without needing a full index when most entries are chronological.
For a planning notebook, I'd use it for a tiny key to any symbols or sticker codes, so I can check what they mean later. For plain notes, I'd skip the setup and start straight away.
I'd leave it alone at first, then use it to note what actually ended up in the notebook once its purpose becomes clear. New-notebook plans can be a bit optimistic.