It is probably never too early to express your own feelings. Expressing what we feel should be second nature, but in our culture, it can often be difficult. If your imput is honest and real, it is never "wrong", but the problem can come in our expectations of another's reaction. If you are thinking it may be too early and you may scare her off, listen to your own inner thoughts too. Telling someone that you have affection for them can be uplifting for the other person, but if it comes with strings and too quickly, it can be a bit confusing and stifling.
It is good to treasure each stage of a relationship and not rush things too. Getting to know one another takes time, and in the process we learn a lot about ourselves as well.