Not to be a party pooper... but it looks like you are getting in on a Sunday morning so I'm not sure how much activity will be going on and what shops are going to be open if you get to Centraal around 7am. We had to catch a train early on a Saturday around 7:30am this spring and while the streets weren't deserted, it was pretty quiet. It doesn't look like the sun is even going to rise until 8:20.

I'd still recommend heading into town but just suggest planning your time wisely. Museums are typically open pretty early daily. The markets are likely open early than the shops. And I wouldn't expect most shops to be open until noon. Personally, favourite thing to do in Amsterdam is just walking around the interesting steets & alleys along Damrak, Nieuwendijk, & Kalverstraat and around the intersting neighbourhoods like Jordaan.