Google's Mueller answered how Search Console handles sitemap uploads but also said there are no set timelines for crawling.

Work on a Google site page while you're offline, then copy it to the server when you're ready for the page to go live on your Google site. Google doesn't allow you to upload HTML files to your ...

1) The HTML file upload: Google provides you with a HTML verification file that you need to upload to the root directory of your site. Once you’ve done that, you just click on the provided URL, hit ...