Is there a way to iterate over specific month or week

There is no time.Date object defined in the standard library. Only time.Time object. There's also no way to range loop them, but looping them manually is quite simple:

// set the starting date (in any way you wish)
start, err := time.Parse("2006-1-2", "2016-4-1")
// handle error

// set d to starting date and keep adding 1 day to it as long as month doesn't change
for d := start; d.Month() == start.Month(); d = d.AddDate(0, 0, 1) {
    // do stuff with d
}