Present or past temporal clauses take the indicative when the action is marked as a fact and refers to a definite occasion (negative οὐ). The principal clause commonly has the indicative, but may take any form of the simple sentence.
A. Temporal clauses denoting the same time as that of the principal verb ( cross2383 A).
ὅτε ταῦτα ἦν, σχεδὸν μέσαι ἦσαν νύκτες
μέχρι ἀπὸ τοῦ ἴσου ἡγοῦντο, προθύ_μως εἱπόμεθα
ὅσον χρόνον ἐκαθέζετο . . . ἀμφὶ τὴν περὶ τὸ φρούριον οἰκονομία_ν, . . . ἀπῆγον ἵππους
ἐν ᾧ ὡπλίζοντο, ἧκον . . . οἱ σκοποί
N. μέμνημαι, οἶδα, ἀκούω often take ὅτε
B. Temporal clauses denoting time prior to that of the principal verb ( cross2383 B).
ἐπεὶ δ' ἐξῆλθεν, ἐξήγγειλε τοῖς φίλοις τὴν κρίσιν τοῦ Ὀρόντα_ ὡς ἐγένετο
C. Temporal clauses denoting time subsequent to that of the principal verb ( cross2383 C).
ἔμειναν ἕως ἀφί_κοντο οἱ στρατηγοί
λοιδοροῦσι τὸν Σωτηρίδα_ν ἔστε ἠνάγκασαν . . . πορεύεσθαι
τοὺς Ἕλληνας ἀπελύ_σατο δουλεία_ς ὥστ' ἐλευθέρους εἶναι μέχρι οὗ πάλιν αὐτοὶ αὑτοὺς κατεδουλώσαντο
When the principal verb is a past indicative with ἄν and denotes non-fulfilment, a temporal clause has, by assimilation of mood, a past tense of the indicative denoting non-fulfilment.
ὁπηνίκ' ἐφαίνετο ταῦτα πεποιηκὼς . . ., ὡμολογεῖτ' ἂν ἡ κατηγορία_ τοῖς ἔργοις αὐτοῦ
οὐκ ἂν ἐπαυόμην . . . ἕως ἀπεπειρά_θην τῆς σοφία_ς ταυτησί_
The negative is μή only when the temporal relation is regarded as conditional.
ὁπότε τὸ δίκαιον μὴ οἶδα, ὅ ἐστι, σχολῇ εἴσομαι εἴτε ἀρετή τις οὖσα τυγχάνει εἴτε καὶ οὔ
The future indicative is rarely used in temporal clauses; and when used refers to definite time.
τηνικαῦτα . . . ὅτε οὐδ' ὅ τι χρὴ ποιεῖν ἕξετε
a. The future is rare because that tense does not usually make clear the difference between action continuing and action simply occurring in the future. ὅτε with the future indicative has thus been almost entirely displaced by ὅταν with the subjunctive.
b. For the future with κέ in θ 318 the subjunctive is probably correct.2399
Temporal clauses referring indefinitely to the future take either the subjunctive with ἄν or the optative without ἄν.
a. The addition of ἄν produces the forms ὅταν, ὁπόταν; ἐπά_ν, ἐπήν (both rare in Attic), ἐπειδαν. ἕως ἄν, μέχρι ἄν, ἔστ' ἄν mean
b. The temporal conjunctions have here, in general, the same constructions as conditional ἐά_ν or εἰ. Thus ὁπόταν ἐά_ν ποτε, ὁπότε εἴ ποτε.2400
The present marks the action as continuing (not completed), the aorist marks the action as simply occurring (completed). The present usually sets forth an action contemporaneous with that of the leading verb; the aorist, an action antecedent to that of the leading verb.
a. The present may denote time antecedent when the verb has no aorist, and in the case of some other verbs: Thus, (ὁ πόλεμος) δς λυ_πήσει ἕκαστον, ἐπειδὰν παρῇ the war
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].