Kaur,
No one can predict how long it will take you to reach a certain level of flexibility. As someone who has been doing yoga for only about a year, I would urge you to simply keep up your practise, and do it mindfully. Over time, you will experience greater flexibility, strength, and balance, but just as importantly, you will also cultivate calmness and inner peace. With time, you will notice that when practising various poses, you will be more comfortable, relaxed, and focussed. In my experience, when this happens, I am better able to get into the pose more deeply, both physically and mentally, which in turn supports the practise overall.
Also be aware that your practise may wax and wane a bit. Some days you may be really engaged, and other times, it is more difficult, either physically, mentally, or both. I think that this is just the normal day-to-day fluctuations that we see in our lives, and that pertain to just about everything. So, on days when you don’t feel really “on” in your practise, don’t worry about it - just keep up your practise and you will reap many benefits.