Yes, you should be able to make ADR's. However, I personally believe they leave a large block open for walk ups. I have a 4:45, (my only other option was 10pm and I called at 5mo out).
You can make ADR's until 5:45pm....then again at 10pm...IIRC. Between those times, they only accept walk up's. The CM I spoke with told me that they'll guarantee you a table if you're staying on Disney property...but it's first come, first served.