I dance American Waltz, too. I was first taught that a twinkle (man's part) began with Left foot forward, then R foot slilghtly, diagonally (!), to the side, and then an opening into promenade as the left foot moved forward in promenade.
More recently I was taught that the 2nd step does not go side or diagonal, but goes forward in closed position (not outside partner) Step 3 still is a promenade step which is actually side and somewhat diagonal to the left.
Thus, if you initiate the twinkle facing Diagonal Wall, you do two steps that are DW, and then a third that is LOD.
Anyway, that's my description. I'll be interested to see how others, especially the int'l style folks tear it apart.
Jerry