Hi Lisa! Thank you for your kind statement about the panel; we are all enjoying helping guests with their WDW trips so much!
You are going to WDW during such a wonderful time; and it will be off-season, too, so the crowds should be light. How great!
Last year, reservations for the the Candlelight Processional dinner package started the first part of July, so I'd imagine it would be similar this year. While nothing has been released through WDW yet, www.allearsnet.com has recently posted a tentative list of narrators for this year. You may want to sign up for the weekly newsletter from allearsnet.com since she will likely announce when reservations can start being made. Once we know, too, we'll certainly share any information through questions we receive -- maybe you could ask again toward the end of June.
The show was shown at 5:00, 6:45, and 8:15 last year and lasted around 40 minutes. So even if you view of the last show at 8:15, you should be let out just in time to catch Illuminations which begins at 9:00.
Candlelight Processional has always been a holiday favorite of mine, so I hope you will have a chance to enjoy it as well.