DON-DON'T FLY IT YET!
The step in a float is on the underside where your float thickens from the aft end towards the forward end. Where your CG of your plane ends up in relation to this, is arbitrary. Casey help this guy out. Fred C - get in here! One of your most important mounting points is not the spinner, but the prop arc. Mount your float tip, 2 to 2 1/2 inches in front (!) of your prop arc. The spread of the floats (on center) should be 25% of the wingspan of your plane. I've seen too many fliers torpedo their planes on take off, and many more tip over because these are not obeyed. Click on my gallery and this will give you some inspiration. The red line on the floats' nose is my prop arc, it's also good to stay away from that area when your engine is running.
Remember also, on take off, don't horse it off the water. Gain speed then apply back pressure. On landing, fly it in, don't chop the throttle as you're about to hit the ripples. You'll have a blast when you're all set up. Good Luck!
Jim Soque