Wow, congrats on the layers! I remember when mine finally puffed up, it felt like a small victory. For that golden color, an egg wash right before baking works magic, but go light or it can get too dark. Keep your oven around 375 and check them often near the end to catch the perfect color. A little steam in the oven helps too, just a pan of water on the bottom rack.
That steam trick with the water pan is a solid move. Saw a baker mention it helps keep the pastry from drying out while the layers set. For @the_grant, I read that using just the yolk mixed with a tiny bit of cream or milk gives a darker shine, but the whole egg is more forgiving. My own take is if you want super shiny, go yolk, but whole egg is fine for just color. The main thing is to brush it on so thin you can barely see it.