First of I want to wish you the best of luck on your first solo!You have truely reached a milestone in your training. Just remember that if your instructor didn't feel confident in your abilities he/she wouldn't of signed you off in the first place.
I still remeber my first solo I was very nervous before takeoff, but after I got up in the air I was fine, and confident. After I got back my instructor cut the back of my shirt off.
After you solo let us know how it went-Good Luck!!