TT #23 · Parshas Tazria · Aliyah 1 · Passuk 3
English: On the eighth day the flesh of his foreskin shall be circumcised.
Chabad.org — Chumash, English translation + Rashi for Vayikra 12:3
Torah Temimah cites Shabbos 132b.
E-Daf — Shabbos 132b · Shas.org · Steinsaltz Center — Shabbos 132b
English: The Sages taught: Circumcision overrides the prohibition against cutting away a tzaraas lesion, whether the circumcision is performed at its proper time or later.
Textual inference
The rule applies both to circumcision performed at its proper time and to a delayed circumcision.