first thing in the morning
Colloquial noun/adverb meaning the very first activity or time slot of the morning, often used in business or daily planning contexts.
I check my email first thing in the morning.
I have a meeting first thing tomorrow morning.
first thing in the morning
Common katakana spelling emphasizing the colloquial, casual tone.
Kanji spelling using 一 for 'first'; common in informal writing.
Colloquial abbreviation of 朝一番 (あさいちばん), literally 'morning's first'.