It seems like an adjective in those phrases. Are you sure that 'early' is an adverb? 我比其他人早来三小时。 the ship arrived 30 minutes early.
Young Mick Jagger The Early Years of the Rolling Stones Legend in 10
会议通知中的early bird deadline是什么意思在国际会议的注册通知中,经常会提到一个术语“early bird deadline”,它指的是提前注册的截止日期。设立这个日期的主要目的.