In Finnish, ‘ilta’ (evening) is generally from 6PM-11PM (18:00-23:00). While we don’t seem to know how Bronze Age Greeks kept time, the Classical Greeks divided the day into 12 hours, with the night being divded into four “night-watch” shifts of 3 hours. Regardless, in our modern times, people generally get off from work around 5-6PM, so the concept of ‘six’ and ‘evening’ can apply to our world today.
Finnish has another word for ‘evening’: Ehtoo, from *ektago. Karelian also has ‘ehtä’, from *ektä. I would like to compare these with two Greek words: (h)Ektos/ektō/ekta (sixth; Έκτος), and Ektelô (To complete, bring to an end; Εκτελώ).
Furthermore, Northern Sami ikte (yesterday) is compared with Greek ektés/ehθés (εχθές). What all of these words seem to have in common is Ekt/Eht, from Greek Ek/Eks (Εκ), which means various things: ‘To move out (of something), to denote change from one place or condition to another’ being the most central to this idea. Likewise, the cardinal 6 (six, vs. ordinal ‘sixth’), in Greek is Eks (Εξ), which can still be seen in modern Greek Eksi (Έξι).
I believe these words may be related to finishing work at 6 in the evening, resulting in people going out to do other things.
Evening; Six = Ekta/Ehta, Ekto/Ehto, Ekso
Yesterday = Ede(s)/Ekte(s)/Ehte(s)/Ekhthe(s)