there have been cases
i personally don\'t know anyone of the cases who were declined and had to go out, but i am sure if you search on this forum and on the FAQ you will find the answer to that question.
as for your question on when is the best time to apply, on the FAQ of this forum, it was mentioned that actually the best timing to apply for a waiver is actually after 6 months to one year of your visa expiration date.
as for some people are subject and some are not, this is true.
1-if you come on J1 as a Medical Student then you are automatically subject.
2-if you come on J1 for other type of training or studies, then you are not subject unless on of those 2 items below is your case:
a- your participation in the program for which you came to the
United States was financed in whole or in part, directly or
indirectly, by an agency of the United States Government or by
the government of the country of your nationality or of your last
legal permanent residence;
b- at the time of admission or acquisition of status under
you were a national or resident of a country which the
Director of the United States Information Agency, pursuant to
regulations prescribed by him, had designated as clearly
requiring the services of persons engaged in the field of
specialized knowledge or skill in which the alien was engaged.
in other words if you your skill is listed under the skill list of your conutry than you are subject to the 2 years.
All those information as well the skill list can be found on the following website:
http://travel.state.gov/jvw.html
it has a lot of information, read it well
good luck
Ziad
the information above are not a legal advice, they are based only on my personal experience and readings from the internet.