When my gen 1 was stock I would launch at about 10k rpm on the track, however on the street if I launched anything over 6 it would spin out. There are a million different opinions on how to take of the "right" way and everyone thinks their way is better and easier on the bike. The way I do it and my opinion on how to do it the "right" way is: I take off with the tac around the 9-10k mark slowly releasing the clutch while adding fuel, my goal is to not let the rpm's drop below the 6k mark. If you drop the clutch too quick with not enough throttle you will bog the engine resulting in a lost race. If you drop the clutch too quick with too much throttle you will flip the bike or (most likely on a busa) you will spin out. It takes practice lots and lots of practice, I do not recommend the next time your riding for you to wrap to 10k and drop the clutch chances are you will wreck. Start slow because even taking off at 3k will send the back end spinning out of control if you drop the clutch too quick with too much throttle.
Just always remember clutch is kill if at anytime something is happening you don't like pull the clutch, unless your in a wheelie then just ease off the throttle, pulling the clutch depending on how high the wheelie is will result in a busted oil pan.
Good luck, be safe and the safest place to practice your take off is at the track. The track is sticky it is a lot less likely for you to spin out. Public streets are good for it but not made for it, its much safer for the bike, you and others for it to be on the drag strip. Plus you can learn a whole lot just from watching other people.