The DOD operational test office has recommended that it is too soon to start pilot training at Eglin Air Force Base due to safety issues with the program. A delay of 10 months is recommended until the results of flight test are more mature.
Doing pilot training too soon can cause problems because the trainees are not rated test pilots. This can cause serious problems if the F-35 is indeed under-tested because of an attempt to rush things through the system so vendors can get their performance bonus.
The F-16 suffered a similar problem when it was rushed into service; including poor documentation of aircraft performance. This resulted in a test-pilot-by-any-other-name problem which ended up getting some people killed.