Yes, this exact thing happened to me with Sun Country. We were booked on a 6pm return flight out of SAN to MSP. A month or two before the flight they cancelled that flight and put us on a 9am flight home. We had a wedding the night before and had to be up at 6am the next morning to get to the airport.
Now, that said, Sun Country is doing whatever they can to stay afloat. Tom Petters put them in a tough spot. I wasn't pleased, but I know that these things can happen, especially on an airline that is trying to do whatever they can to continue to operate.
When you talk to customer service I will bet that you will get nothing but top notch service. Every agent I talked to was super nice and willing to work with me. I looked at moving the flight to a LAX return to MSP but the agent even warned me they "might" be tweaking those schedules as well and sure enough they did. The agent was right on the money. I ended up keeping the SAN-MSP flight they had switched us to. I was glad I did!
They did offer us a $100 voucher for our trouble, which we used to fly to MCO at spring break. They gave us 8 of those vouchers for the 8 of us. Don't know if that is an option for you or not.... our issue was right during the height of the Petters arrest and I am sure they didn't want to lose their fan base.
You have plenty of time, so they are offering you what they can. Cancel for a full refund or take the flight change and move on. This is one of the problems of flying a small (but awesome, IMO) airline like Sun Country. At peak times, they have 2 flights to/from MCO. They only own about 5-6 airplanes and don't have the fleet to offer 6-10 flights a day to a certain destination.
So, flying a small airline like SC is a risk, but one worth it to support the little, local company that is trying to make it work. Again, call their customer service and I bet you will be happy with the conversations you have with them.
Best of luck.
Duds