[Answered ]-Django queryset order by related model with distinct

I achieved this by using Min, as suggested by Anonymous.

Show.objects.filter(
    is_active=True,
).annotate(
    e_count=Count('episodes'),
    start=Min('episodes__start'),
).filter(
    e_count__gt=0,
    start__gt=timezone.now(),
).order_by('start')