I agree with Purush, you shouldn’t apply for AdSense before you have enough content. Also, make sure your website is fully SEO-optimized.
As for your question about indexing, first you need to connect your website to Google Search Console. Also, upload a sitemap and robot.txt file. If your site is connected and individual pages are still not indexed, try the “Fetch as Google” option in the Console. Finally, be patient — it may take more than a few days for Google to index your pages.