Is it advisable to have a website, even if you are not yet published, do not have ANY writing credentials, and do not plan on starting a blog?
Even before you publish, even before you query, it's good to have a place where people can find you. Take this blog for example: if you enter a contest and I like a particular turn of phrase, I might click your posting name, and see a link to your website. I'll click on that just to get a sense of who you are. If there's nothing there, well, no real problem, I was just window shopping so to speak. But why would you miss that opportunity to tell me you live in Buttonweezerville, have a dog, and you're working on a novel about Jack Reacher's daughter?
There's a rule for writers about this: BE READY.
Having a website is part of being ready. It allows someone like me to get to know you long before you're even thinking about it. And in case that idea scares the sox off you: it's a VERY good thing.
There's another rule too: BE REACHABLE.
Think of it this way: if you ran a store, you'd be open even if there aren't any customers actually in the store, or even on the street yet. Your door sign says "we're open" so that people passing by know to come in and buy those lovely shark party hats you have on display.