According to the current schedule you leave Juneau and Ketchikan early 3:00pm/1pm respectively. Early dining won't affect those ports. You arrive Skagway at 7:00AM and leave at 9:00PM, you would have to be back on the ship at 8:30PM. That's a long day and depending what you do in port, will depend on if your ready to go back to the ship earlier. Nothing says you have to eat in the dining room on that night either. You can always do the buffet. It doesn't look like that night would be one of the formal nights. Your other stop Victoria is from 7:30PM - 11:59PM. If the ship docks right at 7:30PM it still has to be cleared giving you a little more time to eat dinner if you choose the early dining. You could always skip the dessert course that night if need be.