The idea that in Matt 25.15f εὐθέως would be inappropriate with the preceding verb is countered by H A W Meyer: "And it is precisely in connection with ἀπεδήμεσεν that εὐθέως is seen to have a peculiar significance, that, namely, of showing that absolute independence was allowed in regard to the way in which the money was to be employed by those to whom it
had been entrusted, which is admirably in keeping with κατὰ τὴν ἰδίαν δύναμιν."
MAubrey wrote:At one point I went through the NT, Josephus, and Philo on this, but my notes are missing from my hard drive right now...
Re the position of εὐθέως in the clause, I don't think there are any examples of εὐθέως in final position in the NA text of the NT; however in the TR and other traditional texts it occurs in Mark 1.31 καὶ ἀφῆκεν αὐτὴν ὁ πυρετὸς εὐθέως, καὶ διηκόνει αὐτοῖς.
Following Mike's hint, I just checked Josephus on the Perseus site and found the following for εὐθέως:
Against Apion: no occurrences.
Antiquities: 16x, of which none in final position.
War: 63x, of which 9 in final position.
Life: 5x, of which 1 in final position.
Here are the occurrences in final position. The translation is simply Whiston's.
War 1.437 δοὺς μὲν αὐτῷ τὴν ἀρχιερωσύνην ἑπτακαιδεκαέτει, μετὰ δὲ τὴν τιμὴν κτείνας εὐθέως, ἐπειδὴ τὴν ἱερὰν ἐσθῆτα
λαβόντι καὶ τῷ βωμῷ προσελθόντι
for when he had given him the high priesthood at the age of seventeen, he slew him quickly after he had conferred that dignity upon him; but when Aristobulus had put on the holy vestments, and had approached to the altar at a festival,
1.454 οὕτως ὡς ἀπογνῶναι μὲν αὐτῶν τὰ κατηγορημένα, διαλλάξαι δὲ Ἡρώδην εὐθέως. αἱ διαλλαγαὶ δ᾽ ἐπὶ τούτοις ἦσαν, ὥστε ἐκείνους μὲν
as to reject the accusations, and to reconcile their father to them immediately. But the conditions of this reconciliation were these, that they should
2.625 τρισχιλίους μὲν ἀπέστησεν εὐθέως, οἳ παραγενόμενοι τὰ ὅπλα παρὰ τοῖς ποσὶν ἔρριψαν αὐτοῦ,
Whereupon three thousand of John's party left him immediately, who came to Josephus, and threw their arms down at his feet.
2.634 τῶν δ᾽ ἠγγέλη μὲν εἰς Ταριχέας ἡ ἀπόστασις εὐθέως, ἐκπεπομφὼς δὲ πάντας τοὺς στρατιώτας ἐπὶ σίτου
συλλογὴν οὔτε
Now this revolt of theirs was presently known at Taricheae; and as Josephus had sent out all the soldiers that were with him to gather corn,
3.183 βουλόμενός τε παρ᾽ ἐλπίδα τοῖς Ῥωμαίοις ἐκτεῖναι τὴν πολιορκίαν, μέτρῳ τὸ ποτὸν αὐτοῖς διένειμεν εὐθέως.
and being desirous to protract the siege to the Romans longer than they expected, ordered their drink to be given them by
measure;
5.77 συνεταράχθησαν ἀδοκήτως, καὶ τῶν ἔργων ἀφέμενοι τινὲς μὲν ἀνεχώρουν εὐθέως, πολλοὶ δ᾽ ἐπὶ τὰ ὅπλα θέοντες
when some of hem left their works they were about, and immediately marched off, while many ran to their arms
6.209b ἠπείλουν, εἰ μὴ δείξειεν τὸ παρασκευασθέν, ἀποσφάξειν αὐτὴν εὐθέως. ἡ δὲ καὶ μοῖραν αὐτοῖς
εἰποῦσα καλὴν τετηρηκέναι
they threatened her that they would cut her throat immediately if she did not show them what food she had gotten ready. She replied that she had saved a very fine portion
6.339 ἐπὶ τὴν ῥίζαν ὑμῶν δραμεῖν καὶ ταύτην ἐκπορθεῖν τὴν πόλιν εὐθέως, ὁ δὲ Γαλιλαίαν ἐδῄου καὶ τὰ πέριξ ἐπιδιδοὺς ὑμῖν
he had run directly to your fountain-head, and had immediately laid this city waste; whereas he went and burnt Galilee and the neighboring parts, and thereby gave you
6.431 ὑπήντα τοῖς ἐπεισπίπτουσιν ὀδμὴ τῶν σωμάτων, ὡς πολλοὺς μὲν ἀναχωρεῖν εὐθέως, τοὺς δὲ ὑπὸ πλεονεξίας εἰσδύεσθαι νεκροὺς σεσωρευμένους ἐμπατοῦντας:
but then the ill savor of the dead bodies was most offensive to those that lighted upon them, insomuch that some were obliged to get away immediately, while others were so greedy of gain, that they would go in among the dead bodies that
lay on heaps, and tread upon them
Life 251a κατέβαινον οὖν εὐθέως, αὐτὸς τί λέγουσιν οἱ περὶ τὸν Ἰωνάθην ἀκουσόμενος.
I went down immediately, so that I could hear what Ionathes’ group would say.