admin.py

from datetime import timedelta

from django.contrib import admin
from myapp.models import CronTask


class CronTaskAdmin(admin.ModelAdmin):
    list_display = ['name', 'get_ist']
    list_filter = ['name']

    def get_ist(self, obj):
        return obj.time + timedelta(minutes=330)

    get_ist.short_description = 'Time in (IST)'


admin.site.register(CronTask, CronTaskAdmin)