If you would get to right source of information, from 800, you could get to 1200 and more in an instant. The only question is if you would like to remain on not less than 1200 on a constant basis or if you would be satisfied peaking that level just once. The right frame of mind to be in is also important.
How long would it take to be 1200?

I see people aren't giving many real answers, I think if you're doing 2 15:15 games a day, you could get to the skill level and be able to beat 1200s in like 3 weeks or less if you really want it. That being said, chess.com gives only like 10/-10 elo per game you win/lose as a beginner, and that number only gets smaller. If you need 350 more then that would take around 2 weeks, if you win every single game. I would say use another account or website to look at openings, and find one you like, but know multiple. I used to play the Italian game every single time I played. And it worked well, at first. But over time I was playing different people and it became less and less effective. So now I use the sicilian defense often, if I'm black and some other openings if I'm white. It might not seem like it now, but it does help just knowing the openings and why they are good specifically. It's not just the knowledge and information it's predicting your opponents personality and how they will decide to play, and then acting on it to beat them. This is why I prefer FIDE (irl games) over chess.com often, because I can see and know my opponent. Anyway I'm gonna stop yapping lol sorry about that,

I see people aren't giving many real answers, I think if you're doing 2 15:15 games a day, you could get to the skill level and be able to beat 1200s in like 3 weeks or less if you really want it. That being said, chess.com gives only like 10/-10 elo per game you win/lose as a beginner, and that number only gets smaller. If you need 350 more then that would take around 2 weeks, if you win every single game. I would say use another account or website to look at openings, and find one you like, but know multiple. I used to play the Italian game every single time I played. And it worked well, at first. But over time I was playing different people and it became less and less effective. So now I use the sicilian defense often, if I'm black and some other openings if I'm white. It might not seem like it now, but it does help just knowing the openings and why they are good specifically. It's not just the knowledge and information it's predicting your opponents personality and how they will decide to play, and then acting on it to beat them. This is why I prefer FIDE (irl games) over chess.com often, because I can see and know my opponent. Anyway I'm gonna stop yapping lol sorry about that,
I already have some openings. I am NOT winning every game. If I was, I wouldn't be here lol.

If you have a solid opening knowledge on mainline and main openings, and have solid endgame knowledge then you'll reach 1200 in as few as perhaps a month or 2-3 (I play only 1-2 rapid games a day mostly 1 so it took longer) middlegame is where I can't help much on as I don't feel confident about my middlegame.
It's the typical blunder check, check for checks, possible attacking chances, calculate how many possible reasonable moves you and your opponents can make, and then in-depth each one, and who will get their attack going before the other. Also never disregard your opponent's pieces on your half of the board because their piece could become a nuisance.
Recheck your calculations once they made their move to where you anticipated they would go because you don't know if there is perhaps a tactic you missed or something. Because whoever can out-calculate the other and start causing the attack will be the one calling the shots just don't leave too many defenses vulnerable to tactics when doing so.

I would like to invest time into chess but I don't have the luxury due to school. If I want to keep pursuing, I can only read some Chessable short and sweet courses and 1 chess.com lesson video per week with some lichess studies and youtube videos. However, endgame and middlegame is where I learned on my own with mate techniques and openings from online.
Why are 100- 1500's even giving advice.
Note:I am not a 1480 rapid.
OP is not asking for advice. They are asking this question: "How long do you think it would take to become 1200? (Rapid)".
That is a question anyone can answer regardless of their rating. And there is no correct or wrong answer to that question.
Notice that OP is not asking for advice on how to get to 1200. They are asking how long the reader thinks it would take to get there.
Also, you are exactly 1480 rapid, I just checked your stats.

Totally depends. I didn't start playing until I was 45 years old and have a wife ,kids, and a job so I'm expecting it will take me a while to get to 1200. If you're younger and still able to learn very fast and have no responsibilities, then it should be a lot faster.

Id say a couple months if you actually educate yourself while playing and dont just play randomly. 1200s know most basic principles which means you also need to know them

Id say a couple months if you actually educate yourself while playing and dont just play randomly. 1200s know most basic principles which means you also need to know them
I know basic principles, my problem is applying them, and even more so, tactics.

I am thinking of putting some actual hours into chess instead of just lurking on the forums, and actually play some games (2 games a day each being 30 min would prob be fine). How long do you think it would take to become 1200? (Rapid)
There's too many factors for us to give an actual answer (such as age, training regime, opponents you're up against [namely if you pick MUCH stronger opponents with very few players lower rated).
I am thinking of putting some actual hours into chess instead of just lurking on the forums, and actually play some games (2 games a day each being 30 min would prob be fine). How long do you think it would take to become 1200? (Rapid)