Happy Tolkien Day!
Tolkien always wanted to publish Silmarillion first but LotR came about first and there was demand for a sequel for the Hobbit. Unwin wanted to publish LotR by itself and it was already spring of 1952.
I love these two paragraphs from Letter 133 to Rayner Unwin.
"As for the Lord of the Rings and The Silmarillion, they are where they were. The one finished and the end revised), and the other still unfinished (or unrevised), and both gathering dust. I have been both off and on too unwell, and too burdened to do much about them, and too downhearted. Watching paper-shortages, and costs mounting against me. But I have rather modifeid my views. Better soemthign than nothing! Although to me all are one, and the 'L of the Rings' woudl be better far (and eased ) as part of the whole, I woudl gladly consider the publication of any part of this stuff. Years are becomign precious. And retirement (not far off) will, as far as I can see, bring not leisure but a poverty that will necessitate scraping a living by 'examining' and such like tasks.
When I have a moment to turn round I will collect the Silmarillion fragments in process of completion--or rather the original outline which is more or less complete, and you can read it. My difficulty is, of course, that owing to the expense of typing and the lack of time to do my own (I typed nearly all of the Lord of the Rings) I have no spare copies to let you. But what about the Lord of the Rings. Can anything be done about that, to unlock gates I slammed myself?"
Thank goodness for Chris Tolkien publishing Silmarillion for him in 1977- we knew the works of his heart were in the First Age.