You can see her profile here:
http://www.sdn48.co.jp/members/ She's very pretty.
It's hard to say when she (and the rest of 3rd generation) will start being active. SDN48 news doesn't come as frequent and often as AKB/SKE and even NMB news does unfortunately.
I assume they will be in the next single (which hasn't been announced yet) and start being added to the stage performances soon. I'd say just to check in with the SDN section at Stage48 (
http://stage48.net/forum/viewforum.php?f=37) every once in a while to see what's up.