Try to Use Following :
dateTimePicker1.MinDate = new DateTime(year, month,day);
dateTimePicker1.MaxDate = new DateTime(year, month,day);
dateTimePicker1.ShowUpDown = true;
dateTimePicker1.Format = DateTimePickerFormat.Custom;
dateTimePicker1.CustomFormat = "MMMM dd";
To disable Days before the first day of current month:
dateTimePicker1.MinDate = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1);
Limit Future Date :
MaxDate
is used as follows
dateTimePicker1.MaxDate = DateTime.Now.AddDays(number of days);