I think you might be ok, it seems like most of the training plans I've used in the past for running usually start about 8 weeks out or so.
http://www.halhigdon.com/halfmarathon/novice.htm
That is the site I followed (I followed the 10k training plan however) and it worked great for me. I see this one is a 12 week plan and starts at about 3 miles so if you started now you could almost follow that to a T if it looked good to you.