well if they get you seated on time you should be fine. We normally eat at there at that sort of time and still have time to grab a drink and see illuminations.
My experience is that a meal at this restaurant is about an hour with a 10-15 minute wait past your ressie so you should be right on time to walk out the front door and see it. Although you will be in a major crowd in that area.
The last few times I have eaten here we had been in and out very fast. Too quickly as we felt rushed. I think you will be okay if you are seated on time. Maybe get there a bit earlier and see if they can seat you then.