We did something similar earlier this summer. Stayed at Contemporary, dinner at 5:30 p.m. at V&A for our 10 year anniversary. Used KNO for our 2 1/2 yo and 8 yo Was our first experience with KNO.
She arrived exactly at 5pm, the requested time. The only negative about our experience is that it took 40 minutes for her to go over the paperwork which could have been emailed to me in advance to have completed when she arrived. We were very late for our dinner reservation, but V&A was fine with that. We assumed we would be back to the room by 9pm, but walked in the door at 9:30 p.m. Were charged for the extra half hour. She told us all about the evening . . . they ate dinner in the room, played games, did crafts, etc. They did so much in the room that they didn't have time to leave the room, although they had my written authorization to do so and I had left cash for her if needed. My 8 y.o was originally wanting to watch the outdoor movie and do the bonfire at the hotel, but said what they did in the room was way more fun.
My 2 1/2 yo who never goes to bed early, was in her jammies and out cold in her bed. Both girls said they had a blast, said her bag was like Mary Poppins . . . never ending toys and projects.
Let me know if you want more information.