I always tell clients to start looking early because it gives them a better feel for the market and lets them hone what they are really looking for. The best listings still sell fast, 1 day, 1 week and if you just start looking when you are ready, you stand to miss a really good one delaying the decision, not knowing if it is the "right one". As for short sales, they are all over the board. Some can move as fast as a regular sale and some can be delayed for quite a while. Banks are far better at it than they were in the past. Some have third party facilitators in place and they move quite efficiently.
Typically when you put an offer in and it gets accepted/approved, settlement takes placed in 30-60 days. Most buyers financing the home like to settle at the end of a month to pay less interest at closing and that means the end of the month following the current month as less than 30 days is difficult for a financed purchase.
As for renting, you have 4 months left. If you look for 2 months to get a good feel you could easily give notice anytime after that when you find a home and have very little if any overlap between settlement and the end of November. Even if you find a home after 1 month, perhaps you could afford to rent for one extra month to enjoy a gradual move. In my experience short sales once approved must move fast to settlement so offering a delayed settlement may not work well with short sales. I have seen banks stipulate it must settle by XX/XX
Hope that helps,