Make it your goal to know more Japanese today than you did yesterday and more Japanese tomorrow than you do today.
I don’t know how many words constitute a functional daily vocabulary in Japanese. There are about 2100 daily use Kanji (okay, 2,136. I looked it up.)
[Before we move on, the joyou (daily use) Kanji have some odd inclusions and odd omissions. This appears to be due to the fact that they are the approved Kanji for use in government documents, and these documents sometimes have to discuss things that many of us don’t discuss in daily life, such as “pig iron” and some uncommon units of measurement.
The daily use Kanji are a great place to start, but don’t feel like you’re bound to it.
My current textbook includes the term for “UNESCO cultural heritage site.” I didn’t learn that one.]
At 20 characters a day, you could learn them all in three and a half months or so. (Check out the “learning the kanji” posts to see what I did.)
Even if all you do is learn 5 new Kanji or five new vocabulary words or 1 new grammatical structure today, then you will know more Japanese today than you did yesterday. Tomorrow, lather, rinse, repeat. Every day you want to be able to say, “I know more Japanese today than I did yesterday.” If you keep doing that, you have something to pat yourself on the back for, and you make progress.
Of course, you could always decide to learn 10 new vocabulary words or even 20 in a given day. That’s up to you. Just learn something. Every day.
Just to drive the point home: Make sure that, every day, you can say, “I know more Japanese today then I did yesterday” and you will make sure and steady progress.