[Galin]

I'm leaning more toward a full year for 1500 myself. Reading the entries 1495-1500, and 1500 again, I get the feeling that matters of chronology within the entry might be of secondary importance to the description of events and beings and so on -- as it arguably should be. In entry 1495 -1500 we have (section 166):

'But when at last the Valar learned that the Noldor had indeed passed out of Aman and were come back into Middle-earth, they arose and began to set forth in deeds those counsels that had taken thought for the redress of the evils of Melkor.

167 Then Manwe bade Yavanna and Nienor to put forth their powers of growth and healing; and they put forth all their powers upon the Trees.'

This seems to say that the fruits of the Trees didn't even exist before the Noldor were back in Middle-earth, and the rest of 1497-1500 is more about the Sun and Moon, their vessels, Arien and Tilion, and so on, than chronology -- similar in wording to Quenta Silmarillion actually, although not exact. VY 1500 notes that when the Moon first arose, for a 'while' the world had moonlight and many things stirred and woke, and that Tilion traversed the heavens seven times before Anar arose. And interestingly, because of the initial design of the pathways of Anar and Isil...

'Thus the first of the new days were reckoned after the manner of the Trees from the mingling of the lights when Arien and Tilion passed in their courses, above the middle of the Earth.'

But Varda changed her counsel (after how long?) and set new courses for the Sun and Moon, and:

(177) 'Therefore by the coming and going of Anar the Valar reckoned they days thereafter until the Change of the World.'

Of course the Annal doesn't end here, but one might assume that what follows is a description that spills into Sun Year 1 -- which isn't that problematic in my opinion, if so, because this is an account from the perspective of Aman, which has further things to note, including the assault upon the Moon and the Hiding of Valinor. Sun Year 1 of the Grey Annals also records Morgoth's reaction to the new lights, so there is overlap, but GA concerns itself more with events of Middle-earth, as expected. In AAm it's the assault on Tilion that greatly inspires the hiding of Valinor, and such a notable event -- given Earendil later -- can hardly be left out of an Aman-based account, even if technically we have spilled into Sun Year 1.

The Grey Annals entry for 1500 has much less to report, but notes that, seemingly at the end of 1500: 'And even a they set foot upon Middle-earth, the ages of the stars were ended, and the time of the Sun and Moon was begun, as it told in the Chronicle of Aman.

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A look back at the Annals of Valinor (the later version as compared to the even earlier version), a preceding concept where 1 Valian Year = 10 Sun Years:

V. Y. 2998 - 3000: The First Ages are reckoned as 30000 years, or 3000 years of the Valar; whereof the first thousand was before the Trees, and Two thousand save nine were the years of the Trees of the Holy Light, which lived after, and lives yet, only in the Silmarils; and the nine are the Years of Darkness, or the Darkening of Valinor.

Towards the end of these nine years, as is elsewhere told, the Gods made the Moon and Sun, and sent them forth over the world...'