When Astral Heron is played with Here to Help , does Astral Heron apply his ability to his own cost when played

Heron never trigger's from Here to Help

No — Astral Heron can't discount its own cost. Heron's ability ("the next card you play this turn costs [2][A][A] less") only affects a card played *after* the trigger resolves. If Heron is your first card played and enters at a battlefield, it does see itself and trigger (FAQ #12236), but the reduction goes to the next card you play, not to Heron. With Here to Help it's doubly clear: the unit is finalized as part of Here to Help's resolution, and Heron's ability is only added to the chain afterward — Heron is already on the board by then, so its own cost (already paid) can't be touched. The [3] discount from Here to Help applies to Heron's cost; and Heron's trigger has never triggered, as the first card played in that scenario was Here to Help (assuming Here to Help was the first card, but even if it wasn't Heron won't trigger).