code: func (j *Job) At(t string) *Job {
  	hour, min, err := formatTime(t)
  	if err != nil {
  		panic(err)
  	}
  
  	// time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
  	mock := time.Date(time.Now().Year(), time.Now().Month(), time.Now().Day(), int(hour), int(min), 0, 0, loc)
  
  	if j.unit == "days" {
  		if time.Now().After(mock) {
  			j.lastRun = mock
  		} else {
  			j.lastRun = time.Date(time.Now().Year(), time.Now().Month(), time.Now().Day()-1, hour, min, 0, 0, loc)
  		}
  	} else if j.unit == "weeks" {
  		if j.startDay != time.Now().Weekday() || (time.Now().After(mock) && j.startDay == time.Now().Weekday()) {
  			i := mock.Weekday() - j.startDay
  			if i < 0 {
  				i = 7 + i
  			}
  			j.lastRun = time.Date(time.Now().Year(), time.Now().Month(), time.Now().Day()-int(i), hour, min, 0, 0, loc)
  		} else {
  			j.lastRun = time.Date(time.Now().Year(), time.Now().Month(), time.Now().Day()-7, hour, min, 0, 0, loc)
  		}
  	}
  	return j
  }
docs: //	s.Every(1).Day().At("10:30").Do(task)
  //	s.Every(1).Monday().At("10:30").Do(task)