Reference

a follower, sub, or bits goal begins.

Goal

• [[[event.type]]] :: "follower", "subscription", "subscription_count", "new_subscription", or "new_subscription_count"
• [[[event.description]]] :: Goal description (your custom text)
• [[[event.current_amount]]] :: Starting amount (where the goal begins from)
• [[[event.target_amount]]] :: Target to hit
• [[[event.started_at]]] :: When the goal started

note: maps to the Twitch EventSub event channel.goal.begin.