ὅτε causal,=“ἐπειδή”: cp. 1318: O. T. 918(n.): Ant. 170.
σὺ μὲν μολὼν κ.τ.λ.: for the absence of caesura, cp. Ph. 101, Ph. 1369, Ant. 1021.
καιρὸς is almost personified here: cp. 75: Ph. 466“καιρὸς γὰρ καλεῖ”: ib. 837 “καιρὸς...πάντων γνώμαν ἴσχων” (n.).
ἴσθι, in the pregnant sense of ‘take care to know,’ ‘acquaint thyself with.’ Similarly in O. C. 1149“εἴσει”=“μαθήσει”.