Many search engines including Google can index a website within an hour to a few week’s time but it depends on a lot of aspects. Generally, there is no hard and fast rule or any standard time to index a website. However, the following tips can help you to index the website faster.
Server Resources Availablity; Make sure that your website server can deal with a reasonable number of requests so when a search engine bot comes to visit the site it has available resources to crawl your website. By resources, I mean the memory limit, bandwidth, and anything that is used when a website is crawled or visited. Many search engines take care of the resources and if they find an overload situation then they reduce the crawl rate too.
Internal links play an important role, the easier bot can recognize or find the webpage the better it can prioritize the indexing process. So make your new content is easily accessible through prominent places. For example; for an E-commerce website, the new products can be placed on the homepage so that the bot doesn’t have to crawl through several layers to find content. If you think your content is important make sure it is available through priority places.
Avoiding unnecessary URLs can also help to focus on the main pages. For example, an e-commerce website that has multiple filter pages or sort filter pages is less useful and can help to lose focus on the pages that matter.
Use of URL submission techniques such as sitemap submission and URL inspection tool or request indexing feature in the Google search console can also help to index the web pages. Sometimes search engines have a ping feature that helps to invite the search engines to visit the website.
I also found that having backlinks from the authority website naturally such as a chamber of commerce website’s link can help ranking faster. You can also share the URL to social media and related websites to catch the eye.
It is also the reality that search engines do not always index all pages of the website due to many factors such as quality, duplication, or search engines think that it is not useful for the users. Even if sometimes a URL is indexed doesn’t show up in the search result or indexed URL can be removed by the search engines.
Find out a quick guideline by Google’s John Mueller on this topic.