When will I be fluent in German?

The short answer is – it depends on you!
Some factors are how fast you learn, what type of class you attend, how many hours of self-studying you do, and which other languages you know. It also matters, if you live in a german speaking country.
According to the Common European Framework Of Reference For Languages this is the average amount of German lessons you take need to take for each level. These are lessons with a teacher, so they are called teaching units. One teaching unit (TU) is 45min.

Beginner Level

A1
80 – 200 Teaching Units
A2
260 – 350 Teaching Units

Intermediate Level

B1
350 – 600 Teaching Units
B2
600 – 800 Teaching Units

Advanced Level

C1
800 – 1000 Teaching Units
C2
min. 1000 Teaching Units

Simply put:

Level A1 takes about 1 year.
Level A2 takes about another year
and for level B1 you need about a year or a year and a half.

However, it’s possible to learn much faster – it all depends on the hours you put in 🙂