that might be pushing it, though it will depend on exactly when you get seated, how important it is to see all the characters at 1900 Park Fare, and how early you want to be in that Snow White line in the park
Logistically, even if you get seated close to your ADR time and get to eat & see the characters bing-bing-bing, it will still take you an hour. So you won't get out until around 6, then you have to get a monorail or boat to MK which can take anywhere from 5 to 15 minutes, then get off/walk down the ramp, go through bag check, go through turnstyles, then get your party wristband, and then get to the Snow White line...there can be long lines for party wristbands between 6 & 7 pm, so that could hold you up for awhile, too.
If you really have somewhere you want to be inside the park before the party starts, I'd get to the park around 5, and get counter service there, just to be on the safe side.