WEEKDAYS = [
  (1, _("Monday")),
  (2, _("Tuesday")),
  (3, _("Wednesday")),
  (4, _("Thursday")),
  (5, _("Friday")),
  (6, _("Saturday")),
  (7, _("Sunday")),
]

class OpeningHours(models.Model):
    user = models.ForeignKey(User)
    weekday = models.IntegerField(choices=WEEKDAYS)
    from_hour = models.TimeField()
    to_hour = models.TimeField()
    class Meta:
        unique_together = (('user', 'weekday'),)

UserOpeningHoursFormSet = formset_factory(UserOpeningHoursForm, extra=0)
hours = [{
        'weekday': day,
        'from_hour': '08:00',
        'to_hour': '18:00',
    } for day in range(1, 8)]
formset = UserOpeningHoursFormSet(initial=hours)

user_hours = request.user.openinghours_set.all()

weekday: Monday
from_hour: '09:00' # user_set
to_hour: '19:00' # user_set

weekday: Tuesday
from_hour: # default initial value
to_hour: # default initial value

weekday: Wednesday
from_hour: # default initial value
to_hour: # default initial value

weekday: Thursday
from_hour: '13:00' # user_set
to_hour: '15:00' # user_set

weekday: Friday
from_hour: # default initial value
to_hour: # default initial value

weekday: Saturday
from_hour: # default initial value
to_hour: # default initial value

hours = [
    {'weekday': day, 'from_hour': '08:00', 'to_hour': '18:00'}
    for day in range(1, 8) if not any(request.user.openinghours_set.filter(weekday=day))
    else
    {'weekday': day, 'from_hour': request.user.openinghours_set.filter(weekday=day).from_hour,
     'to_hour': request.user.openinghours_set.filter(weekday=day).to_hour}
]

hours = []

openinghours_set = list(request.user.openinghours_set.all())
for day in range(1, 8):
    for openinghours in openinghours_set:
        if openinghours.weekday == day:
            hours.append({ fill from *openinghours* })
            break
    else:
        hours.append({ fill with default values })

formset = UserOpeningHoursModelFormSet(queryset=request.user.openinghours_set.filter())

UserOpeningHoursFormSet = modelformset_factory(UserOpeningHoursForm, extra=7, max_num=7)
    formset = UserOpeningHoursModelFormSet(initial=hours,
                 queryset=request.user.openinghours_set.filter())

user_hours = request.user.openinghours_set
hours = []
for day_id in range(0, 6):
    item = {'weekday': day_id, 'from_hour': '08:00', 'to_hour': '18:00'}
    if any(user_hours.filter(weekday=day_id)):
        my_item = user_hours.get(weekday=day_id)
        item['from_hour'] = my_item.from_hour.strftime('%H:%M')
        item['to_hour'] = my_item.to_hour.strftime('%H:%M')
    hours.append(item)