彼の引き際は見事だった。
His timing in stepping down was admirable.
退き際 focuses on the manner or moment of actually withdrawing (e.g. doing it gracefully), whereas 引き時 focuses on judging when that moment has arrived.
Standard kanji spelling.
Alternate kanji spelling using 退 (withdraw/retreat), emphasizing the act of stepping back.
Compound of 引き (hiki, continuative form of 引く 'to pull, withdraw') + 際 (giwa, 'time, moment').