15. ἐν δὲ τῷ ἄρξασθαί με λαλεῖν, and as I began to speak. A somewhat more precise statement than that of the previous chapter, which was (Act 10:44) ἔτι λαλοῦντος τοῦ Πέτρου. It would appear from these words of Peter that he had hardly begun his address before the gift of the Spirit descended.
ἐν ἀρχῇ, at the beginning, i.e. at the feast of Pentecost.