Something else of interest: Had Tolkien published his revised mythology, would he have discarded the whole notion of Valarian Years? The original reason he invented them was because, in the earlier phases of the mythology, the sun and moon did not exist, and so the Valar required a different system of measuring time. But if the sun existed from Arda's earliest days, wouldn't the Valar have measured time in much the same way we do?
Why would they? It's clear from Appendix D of The Lord of the Rings that the Elves don't count time in the same way that humans do. The Valar's conception of time may be as different from the Elves' as the Elves' conception of time was different from man's.