Java moss turned brown/pale

last weekend I started up a new aquarium, my first planted tank.
Most of the plants seems to be alright, but my java moss has lost its dark green colour and turned brown and pale.
I tied it down to drift wood and it's somewhat directly under the light.
No fertilizers in the substrate, nor in the water yet. However I will start dosing pmdd in a few days.
Tank size 540 liter (140g), Ph 7, KH 3, not very much light yet, about 0.7 wpg. My new light hood just arrived today, will get it up and running this weekend.
I also started up a small DIY CO2 a few days ago, just to see how it affected the Ph, will add more in a few days.

Will it get better in time, or what might it be missing?

Thanx!