Congratulations Projectile! Loco and the others certainly have the right idea.
A good number of years ago, my brother and I bought our first SIB (a heavily used ex RCMP one) and the first thing we did was assemble it in the middle of our parents living room (floor boards and all). Mind you, being a Mark 1C, it didn't fill the enire room, but still managed to apall my sister.
This really is the only proper way to Christen a SIB. If you try to smash a champagagne bottle against it, it's just going to bounce back and smack you in the forehead. And then break - spilling champagne all over your living room carpet. For the sake of the carpet, assemble the boat! And post the pictures here.