Should I pocket my cashflow money or use it for principal payment?

[Andrea Lopez]

Hi all, 

I'll be closing on my first 2-family this week and did some initial estimates and realized I'll probably be positively cash flowing anywhere $200-$500 a month. I'll be moving into the basement next year and will need to do some roof work, but am curious to hear some opinions on if I should pocket that extra cash for those home improvements or if I should go ahead and put it into principal payment? I do have the long term goal of cash-out refi in about 2-3 years.