inline_formset auto_id starting from a custom number

Question

Django user here.

I want my first fields in my inline formsets start from a custom number, like 7 for example :

<input type="text" name="prescriptiondetails-7-unit" maxlength="100" class=" form-control-sm  form-control " id="id_prescriptiondetails-7-unit" value="">
<input type="text" name="prescriptiondetails-7-sqf" maxlength="100" class=" form-control-sm  form-control " id="id_prescriptiondetails-7-sqf" value="">
...

here my view

class add_prescriptiondetail_field_form_hx(AddMixin_hx):
    model = Prescription
    form_class = PrescriptionForm
    success_url = reverse_lazy('prescriptions:list_prescription')
    template_name = __name__.split(".")[-2] + '/' + 'prescriptiondetail_field_hx.html'

    wire_dict = wire_dict_init

    def get_context_data(self, *args, **kwargs):
        context = super().get_context_data(*args, **kwargs)

        formset_prefix = 'prescriptiondetails'
        context['formset_prefix'] = formset_prefix

        from django.forms.formsets import INITIAL_FORM_COUNT

 
        from .forms import PrescriptionDetailForm
        from .models import PrescriptionDetail
        form_set = PrescriptionDetailFormSet = inlineformset_factory(Prescription, PrescriptionDetail, 
                                            form=PrescriptionDetailForm, 
                                            fields = ['unit', 'sqf'], 
                                            extra=0,
                                            max_num=10, min_num=1,
                                            
                                            can_delete=True
        )
        
        
        context['prescriptiondetail'] = form_set
        #           
        return context

how can I tell django to start from count 7 and not render the form fields id and names from 0

NB : Not interested in JS solutions.

I've been pulling my hair for a whole day, read the doc in and out ... but without luck

thank you guys