How to get keyword ranking in 20 days

With the long-tail keyword such as this "Best B.Tech College in Delhi NCR", you just need to write about 2,3 posts on your web, then share them to the Social networks, do 5-10 backlinks then you will get it rank top 20 easily from within 1 week

Dear friend

First of all I don't think that you can guarantee rankings with in 20 days for any project or for any keywords.
There are few gurus out there who guarantee those kind of rankings but most of them use black hat techniques . Though those tactics help for quick rankings but in the long run those tactics can invite google penalty.

It will better if you follow genuine white hat techniques like
1 Guest blogging 2 email outrich 3 Brokenlink building 4 forum postoing 5 blog comenting on relevent sites etc.

Yes i think your keyword is not too high competition, you can get good ranking in 20 days, use relevant blog, article posting.

If you have no idea, better hire a SEO Expert for this Job.

Competition is less so you can easily rank on first page with some solid backlinks.

Note-
No one can guarantee top ranking on Google in particular time frame.
Links in this forum are Nofollow so they are not going to help your site.

Getting top position in Google SERP in a short span of time is quite challenging. But if you are targeting long tail keywords with low search volume and low competition, then you have chance to rank on top.

Today keywords ranking does not only depend on quality backlinks, but also on-page activities do matter. So try to build high-quality natural backlinks and do proper on-page activities.

In order to get your keyword ranking, you need to first optimize your webpage for that keyword. Here are some good on page optimization tips:
Home Title Tag: your main keyword should show up twice here, with a variation of that keyword (eg: lose weight and weight loss).
H1, H2, & H3 Tags: these tags are very important(especially <H1>), and should contain your keyword.
Keyword Location Within Text: try to place each your keyword near the beginning of the first sentence of each paragraph (maintaining at least 100 words between paragraphs).
Use Your Keywords as Anchor Text on your page: link to an internal page on your site, and then link to an authority site (eg: wikipedia) that is related to your keyword.
Images: use the "alt tag" and rename your images to your chosen keywords.
Decorate Your Keywords: bold, italicise, or underline your keyword at least one time.
Google Loves Unique Content: your post should be between 850-1000 words and be well structured around your main keywords.

Now, once you have optimized your site on page, you need to focus on getting backlinks that are on high PR sites and dofollow. It helps even more if those backlinks are located within text that is related to your niche and keywords (contextual backlinks). The anchor text to be used should be a mixture of your targeted keywords, variations/synonyms of those keywords, some generic text, and the raw URL.