If they changed it by like 2 hours or more, you are entitled to a refund. Call them. I had a flight scheduled for tomorrow that got changed and I called and got a refund for it (I'm not even in the state so i lucked out there as I was planning on cancelling it myself).

You can also wait and see if they cancel it. I had 2 more flights this week and they both got cancelled recently and I'm getting refunds. They are probably just waiting until a week before like it was for me in the hopes that people cancel themselves for the BS travel vouchers.