初めて
はじめて · hajimete · JLPT N5 · adverb
for the first time
🌱 初 = first, beginning + めて: the te-form of hajimeru, to begin
初めて shares its root with 始める (hajimeru, to begin) and 初め (hajime, the start). Literally it reads as beginning-and, so doing something 初めて means doing it as a beginning: for the first time. Same hajime as in hajimemashite.
初 — clothes radical 衤 + knife 刀
初 combines 衤 (clothes) and 刀 (knife), depicting the act of cutting cloth to begin making a garment. From this concrete image of starting a tailoring task came the extended meaning 'beginning' or 'first'. It is an associative compound, not phonetic.