1 bedroom apartments

[Creig Leu]

I am looking at buying a 4 plex in fort wayne, IN. I have a pretty good feel for the numbers but with this being my first multi family I was wondering if anyone had some insight as to how much turnover I can expect with 1 bedroom apts. I am currently figuring in vacancy at 8% which assumes about 3 months a year. just wondering if anyone had any stories or advice for a starter. 

also any other things I should think about when considering 1 bedroom apts. 

Thanks!