After how many days I need to start making backlinks ?

work with patience before building backlinks for new website,it is not recommended to focus on building backlinks in starting days,you should focus on SEO and creating high quality content before focusing to building backlinks.

It's advisable to focus on building a strong foundation for your website during its initial days, such as creating quality content and ensuring on-page SEO. However, initiating backlink building after 15 days is reasonable.
Begin with a gradual and diverse approach, prefer relevance and quality over quantity. Prioritize obtaining links from reputable sources to enhance your Domain Authority (DA). Remember, consistent, ethical link-building efforts take time to yield results, and patience is crucial.
Monitor your site's performance regularly and adjust your strategy based on the evolving needs of your website and the search engine algorithms.