[Update 1:39PM: If this is a "kickoff" wave for the [d] leg - which according to market internals this would be it - , then we have a solid target in for [d] in both time and price. 1340.75 SPX based on 1 leg of a triangle should have close to a .618 Fib relationship with another. In this case [d] and [b]. [b] wave also took 33 days (close to a Fib 34) so 21 trading days for [d] would make sense.
If the market intends to work off excess bearishness on Intermediate type sentiment indicators (for instance the AAII 4 week average) and turn them bullish again, it will take both time and (persistent) price to do so. Hence why the triangle is nothing to disregard at this stage.