Now, I take no credit for this, I came across this while on tumblr.
If you put your gamertag where it says GAMERTAGHERE, the image will update every time you customize you’re spartan!
https://spartans.svc.halowaypoint.com/players/GAMERTAGHERE/h4/spartans/fullbody
Here are a few examples from people who have already been playing and customized their spartans.
E from Xbox Live division of Microsoft
Major Nelson from Microsoft
Crecente
Tycho Penny Arcade
GiantBombing from giantbomb.com
Nice find man!
Sweet, thanks.
Shame nobody’s mined the assets themselves. Then we could whip up one of those “make a Spartan” pages.
Still, nice find.
> Nice find man!
> Sweet, thanks.
No problem 
Just doing my part in trying to keep myself/ the people on the forums occupied until the 6th!
Scanner looks badass! So glad I get it in my Limited Edition
> Scanner looks badass! So glad I get it in my Limited Edition
I don’t really like how it looks but hey! Maybe it’ll change when I see it in-game. I’m more excited for the Strider helmet!
Cool! Can’t wait to use it!
eeeeeee!
He squeals with excitement.
It legitimately updates!
Some of their armour has changed from last night.
I am very happy with finding this!!