What are are you looking at? What's your cost range? Are you familiar with the area, or do you need advice on what areas to avoid?

1-2 months. I always start looking too soon (3-4 months out) and I'm panicked there's not much on the market. But take a look 2 months out, and there will be a good selection. Don't panic if you don't nab something then, either, because much more will open up in <30 days out from your lease start date. I got my current apartment 3 weeks before the lease start date.

I live in E. Passyunk and the vibe here is pretty solidly "30+ year olds with kids and (some) money." I'd say Fishtown has better nightlife for people in their 20s looking for higher-energy bars. E. Passyunk has GREAT bars (Fountain Porter is a fave), but they're more lowkey and chilled out.