This is one of the keys to a new blog starting today, you need to be able to find those search queries that have been missed by the bigger guys and align yourself to those queries as it will allow you to get your foothold and start gaining some traffic.
Why target low competition keywords for blogging? In many cases this can allow for quicker ranking on new niche websites. Shooting too high can result in no ranking and no income and quickly burnout and quitting. Building quality content that doesn't bounce and makes readers happy is a perfect fit for Google to know your content is valuable.
This is the biggest key between people who launch a blog and hit success fast versus those who build out a blog and write content but they write on keywords that they will never get to page one for which ends with no visitors, but how then can you figure out this key index?
The best place to start is on Google, they provide the largest search in the world and they are the place you want to rank with to get the traffic numbers.
Below is what a Google Autocomplete structure looks like and this will help you start to find possible openings within any niche.
What I show below here is NOT a Google Autocomplete and should be avoided as a target for a post on your site, pay attention as this gets many new bloggers choosing poorly which causes frustration and aggravation.
What I would suggest at this point is that you have an additional tab open to Google Spreadsheets and have a column for "target keyword" and a second column for "competition level" as this will give you a baseline to organize your thoughts and findings.
Additionally I have columns for "notes" and other random things I like to keep on hand to give me additional information should I think of something else, like a closely linked keyword or something I need to add into my post.
Now I wont go too deep into post length as that is a huge can of worms, what I will tell you is that you want to write at least to the level of your competition in most circumstances unless you find a keyword with no real answer provided.
I would always suggest that you really look at the top 10 search results and see what makes them rank first.
If this involves more words or maybe they won the placing because no one has written specifically on the topic, even though their post may be 3000 words long maybe only 300 words is on the topic.
This actually happens quite a lot which makes people believe they can't win without writing 4000 words but this is far from the truth, understand the search intent and answer the search intent with the words needed to best help the searcher.
Most the actual low competition keywords you find will range from under 1000 words to 3000 words, low competition doesn't always mean there is a low word count to the post it is just a way to understand the competition level of the other posts included in the SERP.
The keys to what you are wanting to see is content that has many lower forms of content, things like forums, Quora, and Reddit will typically top this list as they aren't concise information built to cover a topic.
This doesn't mean that you can just throw up short and limited content and just take the spot away, I always suggest you take the time and write a concise post on the topic so this way you earn the top spot and own it for years to come.
They are more a jumble of details on a topic but not in any way that can help a reader to understand as a well outlined post would do. Most forums are also full of personal preference and not as factual of information as a post will have when done properly.
Forums are an amazing way though to get word of your blog out within the niche you choose but do it gradually over time and become a part of the community so that they will instead love when you post your content.
Reddit in many ways is very similar to a forum as the content is very much useful and not at the exact same time as it is more personal feelings and beliefs and less about truth and facts, generally it is segments of super short information provided by Redditors.
Reddit is another place to become a common visitor to niche based Reddit threads and you can get some pulses of traffic and some more street cred within your niche just by being a part of the community.
Quora is just an interesting place as it isn't a forum but more a question and answer system but without any big need to have "qualified" reason to answer.
This can lead to very good answers around 500 words to total hot garbage answers that aren't worth the time to read that you give them.
The last thing that is interesting is other blog pots as the old web standard was to make lots of super short content so there are many blogs out there ranking for content that is incredibly short and not very detail rich, these are prime to be taken along with the traffic volume.
This is the million dollar question isn't it, this will depend highly on the search engine and how they rank and score content and the domain it comes from.
This timeframe from my own posts has been days (super low to zero actual posts) to 8-9 months, if someone could figure this out you would be a millionaire.
What I would tell you to do is what I do, I write the BEST content I can based around the topic itself and then I post it on the site. I manually add it to Google Search Console and Bing to help make sure it gets indexed and starts the aging and ranking process.
The most difficult thing I have come to learn and would express onto you is that you don't waste time checking ranks daily, weekly, etc.
If you really want to know then check each month because a daily check for many people will be 3-5 times each day (miraculously expecting changes) but this wastes HOURS each week.
Hours that could translate into another post or maybe two posts, this is what you need to do, change your mindset and get your site moving forward.
Sometimes you may write something perfect that just never takes off, you can revisit it in a year after you have a year of experience and probably spot right away where you went wrong.
Stop continuing to edit the same post to make it "perfect" instead move to the next post that is in drafts and start moving the needle with the time you are saving.
Hopefully this has given you a better understanding around low competition keywords and how to pick and choose them to give you those wins your new site drastically will need, for it and for your own mental sanity.
Blogging doesn't require being a technical writer and you should not strive for perfection and instead write like you would for a friend, help them and show them you care.
Do this and you will find readers for life who will keep coming back for more, this my friends is how you win over the long term and not just short term!