A question was asked on HTLAL about making a plan to learn a language for a whole year. The person layed out a plan with a bunch of different textbook sources that he intended to complete within that year (about German specifically, in this case), and asked for advice, so here’s my response.
What’s important is not how many months or years you take, but how many hours you spend on it. If you spend only 1 hour per day, then a year might not be enough to reach basic fluency. If you spend more than 3 hours per day, then you might be at basic fluency in a matter of months.
Also, I have to agree with a previous response that there’s no guarantee that you’ll be at a certain level just by finishing a bunch of textbooks. In my view, textbooks can be useful for giving you some of the straight-up foundations of the language, but they also tend to have a lot of boring or useless stuff, like “Schalthebel”, as was mentioned. I had to look that one up, and I’m quite confident in my German vocabulary in most situations that apply to my life.
In order to keep working on a language for a year, I really think you’re going to have to find some more interesting materials than those textbooks. You need to keep up your motivation if you’re going to last for the whole year. I suggest going to native materials as soon as you feel the slightest bit ready, mainly because they’ll be more fun. It would take me a LOT of effort to work on textbooks for even a month, but I’m still watching 1 or more hours of German TV even after I’ve done it for a long time. I’ve watched hundreds of hours of German TV, and there’s still new stuff that I learn all the time, and it’s continually interesting. Can you say the same about textbooks?
In the end, I suggest you go with whatever feels the best to you. If that’s textbooks, then great. But my prediction is that you’ll get bored, so I suggest you strongly consider finding some real German books when that happens, and start working through them. Maybe start with a translation of something you already know, or something that you know has simple language (such as a translation of either Paulo Coelho’s “The Alchemist”, or John Boyne’s “The Boy in the Striped Pyjamas”, both of which have interesting plots but simple words).