Explainer from comments:
"The first wave is impulsive (up) the second wave is corrective (Sideways, and often down) before the third wave, which is most powerful and never the shortest.
The chart shows an expected 3 impulse (sub) waves, to 1850 ish that all combine into the first impulse wave from the bottom. I.E. wave 1 started on the 31st March and will end on 30th of April, May could be sideways, with June being explosive."