That is a good question. But I can't think of a really good answer.
It sometimes depends on if there are any rare special events for that time where they will be allowed in first. It doesn't happen often, but I recall a news event one night, maybe a cast member event another night, maybe another company special event on another night. I usually am down at WDW for two weeks in December.
During those times, I have seen rows blocked off that would normally have been used for Candlelight Processional Package guests.
I usually visit EPCOT several nights during my December vacation, and I notice how long the Candlelight Processional Package lines are on the left side of the America Gardens Theater.
And I notice how long the standby lines are on the right side of the America Gardens Theater.
I even look to see if there is a crowd outside the America Gardens Theater gate where I would sometime watch if the standby line is too long. But only if I can view from the fence. Anyone in front of me would be blocking my view.
Speaking just for myself only and not for anyone else, I would get there about one hour and a half before the show. I know that sounds early, but one time I was even earlier and I was the third person in line for the second show after the first show guests had just entered. But it also depends on how many wheelchairs and scooters are in line, too.
You say that you are using a walker, so they will probably guide you to a regular Candlelight Processional Package seat in arow so that more spaces can be available for wheelchairs and scooters. They will probably ask you to fold your walker and they may even help store it for you until the show is over. Or you could just lean on the folded walker at your seat. This is just a guess on my part.
The first row seats behind the accessible area are also a great viewing spot, too, because of the large space between that row and the accessible row. Cast members don't allow anyone to stand in these areas during the show even for photo taking.
As you enter the America Gardens Theater for the Candlelight Processional Package, they will ask you if you can transfer to your seat. If you say yes, they show you where to park your wheelchair/
scooter and escort you to your seats. If you say no, that you can't transfer, they will escort you to the accessible area to park your wheelchair/scooter and allow your husband to sit next to you.
They usually start at the center of the row and work there way to the outside of the row. If sitting in a non-accessible row, they eventually will ask everyone to close as much space as possible between individuals to allow more space for others.
So to make a long story short, I guess it is up to you.
Maybe a night before your Candlelight Processional Package you could visit EPCOT and just look and see for yourself and see what I am talking about.
Regardless of how long the Candlelight Processional Package line gets, you will get in and get a seat. If you are in a wheelchair/scooter, and the accessible front row is filled, they may try and fill in a few spots in the row behind this where there is one indented space for a wheelchair/scooter. Then when those are filled, they will direct you to the rear accessible areas. It is the standby line that comes in after the Candlelight Processional Package line that may see this more where accessible seats aren't as available.
But I have been in a standby line and I was placed in a front accessible row.
I was just lucky.
That is why they're not really a good answer. Who knows what is going on for each evening or for each show. Is it a very busy night or is there a special event?
If you really...really want a good seat, then the earlier the better to get a seat that you might be satisfied with.
But when I stand in the standby line or outside at the gate, I just enjoy the experience and I enjoy the music and I enjoy the choir singing and I enjoy the trumpets blowing and I enjoy the atmosphere and spirit of the season.
I really...really...really miss this. I don't see why they can't set it up using LED lights. I would always linger around watching the lights dance to the wonderful Christmas music at the end of the day after Illuminations. Oh well.
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