how to change one attribute of a Django form field

subform.py

from django import forms

class MyGenericForm(forms.Form):
    valid_from = forms.DateField(
        required=False,
        label='Validity Start',
        help_text="The first date that this rate is valid.",
        widget=forms.DateInput(attrs={"placeholder": "YYYY-MM-DD"}, format="%Y-%m-%d"),
        input_formats=["%Y-%m-%d"],
    )

# solution to be improved
class SpecificForm0(MyGenericForm):
    valid_from = _same_as(
        MyGenericForm.declared_fields["valid_from"],
        but={"label": "Validity Start Date"},
    )

def _same_as(field: forms.Field, but: dict[str, Any]):
    field = copy(field)
    for attr, val in but.items():
        setattr(field, attr, val)
    return field

# first solution provided by ChatGPT
class SpecificForm1(MyGenericForm):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields["valid_from"].label = "Validity Start Date"

# second solution provided by ChatGPT
class SpecificForm2(MyGenericForm):
    valid_from = MyGenericForm.declared_fields["valid_from"]
    valid_from.label = "Validity Start Date"