I have usually found unpersuasive attempts to derive hermeneutical significance from the order of books in the biblical canon. I have blogged on this before (e.g. here). It is one of the themes underlying my recent NTS article on Matt. 23:35. One of the reasons that such ideas have not found favor with me is that the ancients seem to have known nothing about it. They do not interpret books according to a particular sequence (the Minor Prophets, for example, or the books comprising the Ketuvim in the Jewish canon).
But, Frans van Liere's Introduction to the Medieval Bible (Cambridge, 2014) has reminded me that the ancients did in fact find pedagogical significance to the sequence of Solomonic books: Proverbs, Ecclesiastes, Song of Songs. One should begin with Proverbs, continue with Ecclesiastes, and approach Song of Songs--which speaks of the love of Christ and the Church in the sensual language of human erotic love--only when one has attained substantial spiritual maturity.
This idea already finds expression in Origen's Commentary on the Song of Songs, and it is echoed by Basil of Caesarea, Gregory of Nyssa, Jerome, and no doubt others. (For exact references, see pp. 40-41 of my book.) Van Liere's Introduction (p. 161) shows that the idea still found adherents in the twelfth century with Richard of Saint Victor, Explicatio in Canticum Canticorum (PL 196.409) and Gilbert Foliot, Expositio in Canticum Canticorum (PL 202.1150a-b).
I don't think this overthrows my previously expressed doubts about ancient attestation of hermeneutical significance of the sequence of the canon, but it does provide an interesting footnote to that discussion.