Based on my experience learning new languages (I'm bilingual in English and Portuguese), I would say that it really depends on how much we are willing to put into learning it. Time is relative. BUT, I will definitely guide you with my piece of advice on how time is connected with learning Portuguese.
Stay tuned because you're about to consider one of my boring considerations regarding language learning. Are you ready?
How much time do you have? Are you able to study Portuguese for at least 30 minutes a day? Some people say 10 minutes is enough.
Do you own a smartphone? You can use the italki app on the go; it provides excellent tools to help you achieve the required time you need every day to learn a new language.
I'm sure you can use some additional apps/programs to analyze flashcards and learn new words every day.
What are your learning goals?
One other extremely important thing that will probably affect the time you spend learning Portuguese is: Why? Yes, why are you learning Portuguese? Is it for fun? Travel? Work?
Determining the reason behind your learning path can impact the amount of time, commitment, and effort necessary to learn a new language.
After setting your learning goals, it's time to move on to the "real thing."
Considerations about the Portuguese Language
Portuguese might be tricky! In this article, I'm only going to focus on pronunciation. Would you mind trying to read this word: "cão" (dog)? Now, if you want to, ask someone in the community to check your pronunciation. Did you get it right? "ão" is a diphthong sound that sounds like a short "u" sound as in "puck" or "truck," but that's not all. You must include the "w" sound. The fact is that there is no comparable in English; therefore, the closest is "ow," but you must substitute the "o" sound with "uh." Sounds complicated? It is. Impossible? No.
Now try another one: "Bacalhau" (codfish). This one is even harder. There is a sound in this word that might be hard for non-native Portuguese speakers to pronounce (LH). If you want to, please do the same you did with the previous word. Did you get it right?
"Lh" is actually a sound that doesn't exist in English. In terms of pronunciation, and in my opinion, these are just examples of two sounds that may take a while to master. How much time? I don't know. But you know what people usually say: Practice makes perfect! Here's a list of words that you can try to master: "pão", "muito", "próximo", "manhã", "chapéu", "croissant", "menu", "mas", "café", "leite". Having the assistance of a native speaker will definitely help you out. Please bear in mind that there are also some differences between Portuguese from Brazil and Portuguese from Portugal. We don't have time to go over the main differences. Still, I'm confident that a qualified italki teacher/tutor would explain them to you in class if you're interested.
Time. Time is everything! How much time do you have to learn Portuguese? Establishing a time frame and will definitely help you keep things organized and balanced. What are your learning objectives? Trace them, and after that, determine how much time you have to learn a new language. After that, start practicing! One of the challenges with languages (including Portuguese) has to do with pronunciation.
We have Portuguese teachers here on italki that I'm sure will be more than willing to help you achieve your goals. I would suggest you look for one that suits your learning needs.
So, how long can you take to learn Portuguese? I don't think we can find a definite answer to this question. To put it in a nutshell, it really comes down to the effort, commitment, and dedication that you are willing to dedicate and relate it to your time and objectives. It's really risky to set a deadline for how long a person can learn a new language. Still, I'm confident that practice is essential.
I wish you well in your endeavors, hoping you can keep learning Portuguese in a fun and relaxing way so that your time isn't wasted and you can master Portuguese in no time.