Mayisin kacinda gelmek sen?         (i know it is about me going there in may but dont understand what kacinda means )

 Mayýsýn kaçýnda geleceksin?

What date in May will you come.

Kaç: comes from how many? or which number?

Mayýsýn kaçý= literally: which number of May= free: what day in May or when in May.

thank you Marionin.  i thought it was some thing like that but  never thought how many / which day.