Should I Tell Her How I Feel?

Ok.. I'll try to give you a picture of the situation.

1 year ago I met a girl on a choir-trip in Estonia, and we became good friends when I was there.

Then we went back to Estonia this year and I met her again, and we talked a lot and we continued to talk a lot when I went back, on msn, sms etc.

Now she has asked me if I want to come visit her in Estonia in the end of october, and I have said yes.

I am in love with this girl. I have truely never felt like this in years. I am so in love that I don't know what to do.

My question is: Should I tell her how I feel before I go to visit her? Or when I am there?