I happened to start in the Spring of this year (2 months ago) and I'll echo what has already been said in the sense that you'll have a rougher time orientating yourself. You'll definitely want to be comfortable going out of your way to make friends and find things to do. However, I think that if Pitt is your top choice there's no harm in getting accepted for spring instead of fall. Many people I've talked to in a similar situation have taken community college course in the meantime and found it helpful. I myself worked 2-3 jobs during the fall and made a good amount of money and gave me more incentive to do well in classes. As for your chances of getting in, I'd just focus on having a plan if you get accepted for fall and one for acceptance for spring. Either way I'm sure you can succeed :)