If I start my new website for my business, how much time i require to take my website in top google searching through SEO?
I'm afraid there is no straight answer for this question. The time it takes for your website to rank very well depends on several factors:
quality of backlinks
mobile loading speeds (most recent factor)
The first job is to get your website indexed on Google. Identify your SEO strategy, but take care to avoid spamming.
It also depends on how you create your website. Are you hiring a developer for this, or are you using a website builder? There are a number of website builders online--both free and paid. Please consider creating a landing page before you launch your website. This typically helps you draw more visitors. If you'd like here is an example of a landing page: this page seems to announce the launch of a STEM site. One more factor: if you choose free or paid website builders, consider those that allow you to create and maintain a blog. You can use the blog even after launching your website.
All the best! :)