How much backlinks to build on a day?

I suggest you expand that small niche website to 15 pages or more before building any links. The number of backlinks you can build per day depends on the quality of the links you are building. 1 link per week is enough for natural and editorial links. 2 or 3 links per week are enough for PBN links. 5 links per day are enough for low quality links like forum profiles and article directory links ( I wouldn't advise you to point these kinds of links directly to your site).

As many good ones as you possibly can. There is no limit.

Recently, the penguin 3.0 is out by GG and this danger would make a negative impact on "thin content" micro niche site and poor massive backlink and PBN, so my advice is keep publishing more content consistenly first and just focus on little link building. I choose guest post and outsourcing the content to post on hight authority article directory and website like medium, hubpages, yes, very little but premium link.

My sites are usually around 15 -20 pages. In order to get superior rankings it has to be properly silo'd.

When I promote a subpage on my site I will build 1 PR link plus 5 Social Addr backlinks. Then wait for up to 10 days. Then my page re-ranks higher. Then i'll do the same and wait for a week. During the wait I will do the same system to another subpage on my site. This all looks natural to Google.

So little bursts of backlinks and wait. Regarding the PR domains. I will buy a domain with a minimum Majestic SEO Trust Flow (TF) of 15 and higher. Back when Google actually updated Page Rank I noticed that a domain with a TF of 20-30 has a page rank of 2-3. The domain also must have some good incoming backlinks to justify the TF. Like an incoming PR 2 or 3. And I use Maj TF to estimate the PR of the incoming backlink domains.

So I will put 1 original article on the home page with a link back to my money site. Then I add 3 posts that consist of 1 sentence and a youtube video. So the only backlink on the home page goes to my money site. No footprints for Google to see and they should survive a manual review by Google.

I have page 1,#1 rankings for a couple review type keywords that get 10k or more searches per month. It's only taken 5-7 of these PR domains and social backlinks over the course of 2 months to rank. But you have to do this with multiple pages on your site not just one.

On a side note: Try to vary the anchor text of ALL backlinks. And each page on your site needs to be based on a theme, not keyword. Google LSI keywords. And don't try to rank the homepage of your site for a keyword. Does Amazon try to rank it's home page for refrigerators? Nope. I always have a branded domain name. I build some links to the home page but not many. You want to rank your subpages.

Not easy to say the exact number but you need to track your website's organic traffic with semrush or spyfu to see the results of your link building procedures.

article ,block ,forum posting,social book marking etc.through get back link

It does NOT matter, you can build as many as you like or are able.

Also those 5 pages site is fine if those 5 pages are long and well-written otherwise yeah do add a few more pages if they aren't.

There is no limit but the only quality matters a lot. So build quality and relevant links as much as you can.

it doesnot matter how many link you have build ,but it matter how many good quality of link you have build.

I don't think it matters, you should just build links at your own pace. Maybe today you have a lot of time, comment on lots of websites, maybe tomorrow you're too busy to do anything regarding backlinks
There isn't a fixed rule when it comes to this.

There is no specific number of links you should get as long as they are good.

These people saying get 1 of these 3 of these 5 of these it's all B.S.

What happens if your site went viral and you get 20,000 back links in one shot because people from other high quality sites are linking to your content.

Google won't hurt you for that. This happens a lot, look at viral videos.