An adverb meaning 'at the earliest' or 'at the soonest' — indicating the earliest possible time something can happen.
商品は早くとも来週の水曜日に届く予定です。
The product is scheduled to arrive at the earliest on next Wednesday.
その計画が実行に移されるのは早くとも半年後だ。
The plan won't be put into action until at least six months from now.
彼が戻るのは早くとも三日後だろう。
He probably won't be back any sooner than three days from now.