The answer to both is 8:00 - 9:00.
I have my itinerary from my honeymoon. Park hours and Wishes are listed as:
Monday 9/13: MK 9 - 8:30, Wishes at 8:30
Tuesday 9/14: MK 9 - 9, Wishes at 9
Wednesday 9/15: MK 9 - 8, Wishes at 8
Thursday 9/16: MK 9 - 8, Wishes at 8
Friday 9/17: MK 9 - 8, Wishes at 8
Saturday 9/18: MK 9 - 9, Wishes at 9
Sunday 9/19: MK 9 - 8, Wishes at 8
Monday 9/20: MK 9 - 8, Wishes at 8
Tuesday 9/21: MK 9 - 9, Wishes at 9
Wednseday 9/22: MK 9 - 8, Wishes at 8
Thursday 9/23: MK 9 - 8, Wishes at 8
Last year was the first year Wishes was offered in September. It started in October of 2003, so that's the pattern right there!
Before Wishes, The Magic Kingdom closed at about 7, except on weekends when they had Fantasy in the Sky later on.