{While the day was coming on} (achri hou h(886d)era (886d)ellen
ginesthai). More likely here achri hou (for achri toutou
h(9369)) with the imperfect (886d)ellen, has its usual meaning, "until
which time day was about to come on (ginesthai, present middle
infinitive, linear action)." That is Paul kept on exhorting or
beseeching (parekalei, imperfect active) them until dawn began
to come on (cf. verse  39  when day came). In  Heb 3:13  achri
hou with the present indicative has to mean "so long as" or
while, but that is not true here (Robertson, _Grammar_, p. 975).
See on 涉c 2:46| for the same phrase for partaking food
(metalamban(9320)troph(8873), genitive case) as also in  27:34 . Paul
wanted them to be ready for action when day really came.
"Fourteenth day" repeated (verse  27 ), only here in the
accusative of duration of time (h(886d)eran). It is not clear
whether the "waiting" (prosdok(936e)tes, present active participle
predicate nominative complementary participle after diateleite,
Robertson, _Grammar_, p. 1121) means fourteen days of continuous
fasting or only fourteen successive nights of eager watching
without food. Galen and Dionysius of Halicarnassus employ the
very idiom used here by Luke (asitos diatele(935c)). {Having taken
nothing} (m(8874)hen proslabomenoi). Second aorist middle
participle of proslamban(935c) with the accusative m(8874)hen rather
than the more usual m(8864)en. Probably Paul means that they had
taken no regular meals, only bits of food now and then.