Keeping a secret

Jade • 32yr old living in Jersey City with the husband and the dog. This is is our first pregnancy due 1st Sept!
I'm 5 weeks and 3 days today. I'm about to speak to my best friend who lives abroad and I REALLY want to tell her the good news. I know it's very early but this is my first baby and I am SO excited. We are so close I can't describe it and we Skype all the time so I just really want to tell her. What do you think? 
My first appointment with my OBGYN isn't until 26th Jan which seems so far away (I'll be about 8 weeks by then). I know I should at least wait until then but keeping this secret is killing me.