Keep Coding

I have a model "Timings" that goes like this.
weekday = models.CharField(choices=constants.WEEKDAYS, max_length=10)
start_time = models.TimeField()
end_time = models.TimeField()
lab = models.ForeignKey('Lab')
I had to override the form in django admin and display it as inline in Lab form. I created a form for Timings model and excluded all model fields and introduced some form fields.
day = forms.CharField(label="Day", required=False)
start_session1 = forms.TimeField(label="Session-1 Start", required=False)
end_session1 = forms.TimeField(label="Session-1 End", required=False)
start_session2 = forms.TimeField(label="Session-2 Start", required=False)
end_session2 = forms.TimeField(label="Session-2 End", required=False)
My purpose here is to display a table like structure to user in inline. & rows for the 7 days in the week with storing upto 2 sessions per day.
I have overridden the form's save method. Now my instances are getting saved in the DB but in edit mode, I need to display the already present instances in the DB according to the same structure of the form. I ran over the concept of formsets but could not figure out how to override the initial values dynamically.
Can somebody help? Stuck at this problem for a week.