Parashas Bo · Shemos 12:8 · TT note 6
Torah Temimah on Shemos 12:8, note 6 (on בַּלַּיְלָה) points to Tosefta Pesachim (end of ch. 2).
Sefaria — Exodus 12:8
Sefaria — Torah Temimah on Exodus 12:8
Sefaria — Tosefta Pesachim
English: From when is their time of eating? From when it grows dark. If one did not eat from dark, one may eat all night. If one did not eat all night, one may not eat them further.
Practical boundary of the nighttime mitzvah: from nightfall through the night only.
Eating of the Pesach begins at nightfall and may continue only through that night.