Not bad at all! I would say that, in general, your timing is spot on. (For instance, the courtship of Fëanor and Nerdanel takes place after the birth of Fingolfin but before the birth of Finarfin, IIRC.)
I see that you have expanded the beginning of the season, with the journey and the elves of Beleriand, rather than the time in Valinor, to fill the 'empty' three episodes. I don't think that's a bad idea, but I do think your episode 2 and episode 3 can be combined....we have an hour of TV to do this, so the Valar aren't going to stand around and talk about their idea for more than 10 minutes. But the other expansions look good to me, and I like how you've kept the Sindar and Sauron storylines intertwined with the main story.