Flip the stock over and align the stock with the saw blade to the proper top width of 8 inches for the next cut. (Use the scrap material as a jig, aligning it with the stock material, and clamping it to the table saw as shown). Make the next cut.
It may be necessary when cutting a pyramid to make a 1/4" cut from the stock to true it back up before turning it over and aligning it against the jig. (This will only be necessary when cutting a pyramid.) After each cut, flip the stock over and realign the stock material to the jig. Proceed until all pieces are cut.