I have updated the 17.6 WEEK cycle chart as shown below. You can see that every third cycle corresponds with a high turning point and the subsequent low usually follows within the next half cycle (i.e. the next 8.8 weeks).
The dates are from an update of this original post back in 2013. The next high date is 18th May 2015.
The bigger picture looks like this:
From my 17.6 year stock market cycle, shown in full below: