It depends on what you are trying to accomplish.
There are two places where you are asked about being a fulltime student. In the personal info section answer no, if you were not a student for parts of 5 months. This may prevent your parent from claiming you as a "qualifying child" dependent.
Later in the program, If you are entering your 1098-T to claim a tuition credit or scholarship, do check half time or more. It's OK to check full time, even if you were only briefly FT, but "half time or more" gets you the same tax results.
