{Was now come} (en t(9369) sunpl(8872)ousthai). Luke's favourite
idiom of en with the articular present infinitive passive and
the accusative of general reference, "in the being fulfilled
completely (perfective use of sun-) as to the day of
Pentecost." Common verb, but only in Luke in N.T. In literal
sense of filling a boat in  Lu 8:23 , about days in  Lu 9:51  as
here. Whether the disciples expected the coming of the Holy
Spirit on this day we do not know. Blass holds that the present
tense shows that the day had not yet come. It is a Hebrew idiom
( Ex 7:25 ) and Luke may mean that the day of Pentecost was not
yet over, was still going on, though Hackett takes it for the
interval (fifty days) between Passover and Pentecost. Apparently
this day of Pentecost fell on the Jewish Sabbath (our Saturday).
It was the feast of first fruits. {All together in one place}
(pantes homou epi to auto). All together in the same place.
Note homou here (correct text), not homothumadon as in
 1:14 , and so a bit of tautology.