I don't think it's beneficial for
SEO, and I don't quite understand the concept of "letting Google know that something is coming there." Google identifies what is currently present, and I doubt it would predict that something will be included there in the future. Even if it did, I don't believe it would reward you with better rankings than sites that already have the content available.
I was in a similar position a few years ago when I wanted to publish a new website with only a few pages. The advice I received was to wait. Do you have a deadline in mind? Are you determined to publish it no matter what? While you don't need hundreds of pages (the number will depend on your niche), it's better to cover the basics and provide a good user experience for your readers.
In my opinion, publishing empty pages could do more harm than good. It could decrease the value of your website overall, waste your crawl budget, and even lead to potential penalties from search engines.