There is no way to tell you how long the wait for a Stan class is. You could call to find out how many are on the list.
They are running a class of about 6 people now, and there are quite a few high time people here as instructors. So, alot of people could be leaving at any time. People have been steadily getting interviews and class dates. Usually those applying have 1000-1500 hours, with about half that multi-engine time.
I have not kept tabs on the 'success rate' of current interviews. In the past it worked out to about 70-80% or a little higher. Usually those who worked hard made it.
For those currently on the 'wait' list, there are some good opportunities. FSI has internships where those on the list can go to a FSI Training Center for a 90 day internship. You work in different areas of the Center to learn how they operate. You also get a SIC checkout in at least 1 jet aircraft. This is the full training you would get for a type rating. You can then be a 'co-pilot' for customers who come for training in 2 person aircraft without a training partner. It is a good way to make some contacts and network. It also pays $7hr when you are in training and $14hr after you have completed the SIC training. Some have had their internship extended beyond the 90 days. In addition you can take enrichment courses such as 'Weather Radar' or 'International Operations'. I think that you can also get qualified to teach some of these courses.
If you instruct here you can also go do the internship, except it is for a year and you get a type rating. If you want to go corporate, this would be a good way to meet a potential employer and some have been hired in this way. They also offer an internship with ASA that is like a traditional College Internship.
While there is still a wait list, there is also alot of opportunity for those who want it. The internships are something no other school offers, and you can always get another instructor job close to home while on the list. If you want to come back when called, great. If not, you still get some of the best training available.