Need to clean and brighten?

Hi everybody,

I'm new to this so apologies in advance if the question doesn't make sense.
I live in Chicago and have a private deck on the roof of my building. We bought the place in November and the deck was built a few months before then (I think just after the summer). They used WeatherShield wood and I don't think they treated it in any way after installing it. I have a couple of questions:
1. Is this the right time to stain it? Is it too early?
2. Any advice on what type of stain would work best?
3. Given that it's less than a year old do I need to use cleaner and brightener before staining or will a wash be enough?

Thanks in advance for your help. I'm attaching a couple of pictures of the deck as it is today.