I had pneumonia just under two years ago. I actually tried to run Brighton marathon with it (didn't know I had it at that stage.)
It took me approx 5 weeks until I felt up to running again and probably a couple of months before I felt I was back to where I was before. It wasn't the easy runs that were the issue it was the faster stuff that took a while to come back.
As RicF says take it very easy for a few weeks and build up slowly.
I called them yesterday and i got the impression they hadn't sent them out, cutting it a bit fine but she did say it'll be here today (it wasn't) or Monday. I'm a bit worried if it doesn't show up Monday I'll be traipsing up town on Saturday to collect my race pack.