Open the models.py file of your utils package, and insert the following content there:

# utils/models.py
from django.db import models
from django.utils.translation import ugettext_lazy as _

class CreationModificationDateMixin(models.Model):
    """
    Abstract base class with a creation
    and modification date and time
    """
    class Meta:
        abstract = True

    created = models.DateTimeField(
        _("creation date and time"),
        auto_now_add=True)
    updated = models.DateTimeField(
        _("modification date and time"),
        auto_now=True)