I'm totally new to bonsai. I've been poking around and reading, and figuring out where to start. I'm in New York City, zone 7B.

What I've learned so far? I know nothing. I'm going nursery hunting soon, for some cheap material to screw up on and learn and learn some more.

Last Earth Day the (ex) GF comes home with a blue spruce cutting from work event. I thought it's be swell to grow into a mini Christmas tree we could bring inside a few days around Christmas and grow outside the rest of the time. I may be ignorant about bonsai,but I know a good bit about gardening so I got a large planter to keep a significant amount of soil around the roots for over-wintering (and hoped some).

It's grown from a single branch 10" cutting to this http://i.imgur.com/mcVJ5Yf.jpg, which I imagine has 5 years to go before I can do anything with it.

But... do I need to do anything now to prep it for then, when I'll hopefully know more, and it will have a lot more trunk size (the trunk has doubled in about a year, which is nice, but not nearly enough).

Th itchy part of me wants to lop the top off to make it grow more branches down low, but see above: I know nothing about bonsai.

Basically, how do I keep this safe for 5 years?

edit: I realize spring is the wrong time to cut anything, so I'll likely wait until fall to prune, but still hunting advice.