Right now there is a six to 12 week wait just to get to Jacksonville to answer phones. After that, you can expect six weeks before being assigned to a location to teach. Generally, its first come first served as far as jobs go. Rarely someone will impress them enough to move to the top of the list, but this is very difficult. I am currently looking for a job for the time being (I have a family to support).
If you are willing to go to any location, then the wait may be reduced some.
On average, the Sacramento location is the busiest, at least that's what I have heard. We have had 14 to 16 Career Pilots at the location at one time (most at different stages). However, it's not so busy where you will not get individual attention.
I was fortunate on my cross country travels. My partner and I flew all the way to Jacksonville Florida and back. This was a great adventure. Cross country flights start a day or two after completing the instrument rating. Some of the career pilots didn't have the fortune of making it all the way to Florida but most get to at least Texas.
Career pilots at ATP don't really make the company money. ATP simply uses the Career Pilot to deliver aircraft to different locations for maintanance or where there is a greater need for the aircraft. ATP makes its money from the short program people (ATPs, multi add-ons, etc.). Speaking of maintance, I was very impressed with the Seminoles that we flew. ATP ownes a large group of older Seminoles (1979ish) and new Seminoles (2000/01 models). The older models have one Garman 430 GPS and the new ones have two 430's. The company is very safety conscience and has a wonderful maintanance program.
Overall, even with the wait after completing the program, there is no better flight school in the country. Most all of the time acquired is multi-time. You will go from private pilot to instrument, multi and single commercial, MEI, CFII, CFI in about 95 days with a guaranteed fixed price of about $35,000 (including examiner fees). It's fast and fun. Some are not able to take it in that fast, but for those who can handle it (you know who you are) it great. Let me know if you have any other questions.