How to file dependent's length of stay for Turbo Tax Premier?

Hello,

I am divorced and have joint custody of our son.  My son stays with me for 216 days out of the year, which translates to 7.2 months.  Do I enter 7 months or 8 months for Turbo Tax Premier?  Or do I enter 12 months because my son is with me the majority of the time, 60% of the time?

 

Thank you.