How long should it take me to make my game

Too little information to judge.

Things depend on your skills. If you're a good programmer and you're proficient with photoshop or GIMP or some other program that lets you draw your own art, this might in fact get done in a month of two.

But if you were a person like that you would not be asking questions like this...

So if you've never programmed before or you only know the basics, this is your first game, and you don't have any solid documentation written down... You'll probably take well over a month (at just 2-3 hours a day) learning the skills needed to make your game. And only then start on your actual game.

Learning while doing is not a good practice on something you want to sell. Because as you learn more and more, you will have to redo your older work, as you realize what a complete idiot you were when you wrote this or that script. (Trust me, this is common). So don't expect to start on your actual product until much MUCH later.

As an example, it took me a year of university studies of c++ to start work on my own 3d engine and game along with it... After a months work I realized the futility of the thing and tried unity. At which point I re-created my entire progress in 2 days. But I studied programming.

I'm an indie developer working on a 2d game for android, and I work on the game maybe 2 hours a day on average, five days a week. It's been about a month since I started and I've already got mostly all the basic game mechanics, art, and coding done. Now I just need to make more levels. So I don't think it will take that long. 6 weeks is possible, if you work hard. Three hours a day at least, assuming you are good at Unity.