Step 4: Bracing
As you can see in the photo, the ends of the flooring run wild -- you will trim them later. Find a rough center and align the X so that it crosses every floor board. Countersink, pre-drill, and screw the X into every board. Hitting every board is crucial; this will ensure stability in the long term, keeping the table top from twisting and bucking too much with moisture and temperature changes over time.
To brace the legs, lay a straight edge across them, then use an angle finder as shown. Transfer the angle to the chop saw and cut one brace for each side. Glue and screw mid-way down the legs. I counter-sunk the screws and then used a plug-cutter to make dowel plugs to cover the screw heads. This step is optional, but adds to the finished appearance. Lacking a plug cutter, use manufactured dowels, but be aware the color and grain match will probably be off.
Now that the top is braced and sturdy, run the whole table through the table saw to trim the tongues and grooves off the long edges and even up the short edges. Use a sled to make the cross cuts. This can also be accomplished with a circular saw -- just be sure to clamp down a guide board so your cuts are nice and straight.