Timing-Based Recall: 'Critical stage' questions usually point to the stage where a resource shortage causes the BIGGEST yield loss — learn this stage by name.
Crown Root Initiation (around 21 days after sowing) is when wheat develops the roots it will rely on for the rest of the season, so missing irrigation here is the costliest mistake.
Tillering, flowering, and dough stage are all important too, but none causes as sharp a yield drop from a single missed irrigation as CRI does.