Holweck, p. 335, gives a date of 25 December, but Spanish sources attest the 27 December date.
On Dec. 27 (between Stephen and John) in I-VEcap (Verona) Codex Veronensis LXXXIX; after Stephen and before James, brother of the Lord (and then John) in Léon 8, GB-Lbl (London) Add MS 30844, E-Mn (Madrid) MSS/10001, E-Mh (Madrid) Cod. 30. Seemingly in January (between 8 and 21?) in GB-Lbl (London) Add MS 30852.