4:6 already. Paul accepts the inevitability of his death, even if it may still be several months away.
poured out as a drink offering. This metaphor for death (cf. Phil. 2:17) is taken from the language of the Old Testament sacrificial system. A drink offering of wine was poured out in the sanctuary as an offering to God (Num. 15:5, 7, 10; 28:7). Paul understands his impending death as an offering to Christ.
my departure. Another metaphor for death (Phil. 1:23). Paul held steadfastly to the hope and assurance of a destination beyond the grave (v. 18).