How soon to get a new I-20 form a community college depend on the policy of the college, if he can't get it before fall semester,he can choose to leave the country temporarily,& reply a new student visa with
new I-20 of next semester later, usually it's easy since he keep his good record.Another way is file an I-539 for B2 status, & withdraw it later when he find new
I-20,if so,he may be meet trouble when he apply a new visa in China in future.