Just received a notification that my HEL-ORD flight next June has changed. Booked in AY J via AA using AA miles.

At first glance, I thought I was leaving four hours later, but they actually have me on the same flight number but 20 hours earlier, thus losing a day of my trip. (Not sure if the flight is no longer flying on the original date or if, oddly, they moved me to a day earlier despite the same date being available.)

First time dealing with an AY flight change. If I want to depart on the original date or a later date, should that be an easy request, or does the fact it's an award ticket perhaps severely limit my options? Thanks.