Here you go. I've tried to make a timeline of the whole thing:
October 2019 - I entered the pool finally after getting my WES ECA, which had taken ages, at a CRS of 463. (I have a masters', max IELTs, my wife has two degrees, max IELTS, but unfortunately we are both in our mid-thirties). When we started planning this immigration (March 2019), 463 looked like a shoo-in for an ITA.
November 2019 - The CRS had shot up and my birthday has arrived. My CRS drops to 458. I decide to start learning French.
Nov-Dec - My wife helped me learn the basics, she had already studied French in school (couple of decades ago!) and knew enough to help me progress to A2-B1 quickly.
Dec-Jan-Feb - I spent a lot of time listening to the Coffee Break with French podcast (every day during office drive and in the gym), learned grammar textbooks from scratch (Basic, Intermediate, a bit of Advanced), started writing essays for the writing section, started speaking in French to my wife for ~15-20 minutes a day, watched French news daily (TV5 Monde or France 24), did many TV5 apprendre exercises online (free).
Feb 28 - Wrote TEF the first time and got B2 in all 4 skills. But only 8 points added to the CRS. I moved from 458 to 466.
Mar - FSW draws stopped.
Mar-Apr-May - Focused more on the speaking and writing parts. Increased french speaking a little more, while continuing to listen to news, more documentaries, Wrote A LOT of essays and fait divers. Started reading french books. Finished 2 books by Fred Vargas (This is one of the most pleasurable side-effects of learning French for me.. discovered an excellent crime novelist).
June 8 - Wrote TEF the second time as soon as exams restarted in South Africa after the lockdown. Got C2 in Reading, C1 in Writing, C1 in Listening and B2 in Speaking. 8 more CRS points. I've moved from 466 to 474.
So roughly 7 months in total to get the 16 points.
Now for all I know, FSW draws might get delayed a lot more and I might have to aim for the bonus 30 points also. So I'm not gonna stop learning French. Leaving the immigration part aside, it has been a really joyous experience and it's always great to have a new language to communicate with.
The main thing I'd advise for a beginner is to get the grammar in order first. So you must study the grammar textbooks. Once you get the hang of it, it's a really solid foundation to build on. Then the sources I mentioned in my timeline would all be really useful. They are all free. There are many more paid ones available online which could help you as well. Getting a partner who wants to learn French or who already knows some French could be really useful as well. Learning a language is far easier as a team task than as a solitary task.
Lastly, what's as critical as anything else is to have an inclination/passion to learn a new language. If you don't like learning new languages, it's going to be much more difficult. I suggest considering a Canadian degree as an alternate to French if that's the case.