Change your default alert times for Calendar app in iOS

When you add a new event in Calendar app for iOS, by default there is no alert created. You can actually setup a default alert time so that Calendar app for example will create an alert 1 day before at 9am automatically when you’re adding a new all-day event. 

Change the default alert time in Calendar app

To change the default alert times, go to Settings > Mail, Contacts, Calendars > Default Alert Times. You can adjust the default alert for Birthdays, Events and All-Day Events.