Grim, Grinning Greetings, Anna! I'm so glad you decided to swing by planDisney with your question and it'll be my pleasure to help you.
You, my friend, have secured special event tickets to the most coveted Halloween festivities of the season, Oogie Boogie Bash - a Disney Halloween Party! I have a couple of thoughts for you that I hope will answer some of your questions.
As you might know, your separate event ticket to Oogie Boogie Bash will grant you access to the party hours beginning at 6:00 PM on the event date, plus additional mix-in hours beginning at 3:00 PM so that you can enjoy the magic of Disney California Adventure Park! If you wish to enjoy an early dinner at Lamplight Lounge on that day, my recommendation is to make your dining reservation between 4:00 PM and 5:00 PM as that time frame represents the current posted operating hours for Lamplight Lounge's dinner menu on the Oogie Boogie Bash dates. Dining reservations earlier than 4:00 PM will likely reflect the lunch menu, which is also delightful! As with most table-service restaurants, reservations open 60 days in advance of your visit, and I highly recommend making them on the website or via the official Disneyland mobile app as soon as they become available, as this is one popular dining location among Guests!
Now, Anna, if you only have the special event ticket to Oogie Boogie Bash and you are not planning to purchase or use a standard admission ticket for the same date, then you are able to enter Disney California Adventure Park any time after the mix-in hours begin at 3:00 PM. It is not necessary to make an additional park reservation for the event date. However, if you wish to extend your time in the theme parks, then you would need to purchase a valid admission ticket and make a theme park reservation that day, which would grant you all-day access! Then, when it comes time for the spine-chilling events of the Oogie Boogie Bash party, just scan your special event ticket at the gates to stay and enjoy the festivities throughout the evening!
Speaking of special dining events during Oogie Boogie Bash, did you know that Wine Country Trattoria is offering a parade dining package that includes a prix-fixe meal and a reserved standing area to watch the Frightfully Fun Parade? Or, if sweets and treats are more your style, you could book the Oogie Boogie Bash Dessert Party which includes reserved seating in front of Sonoma Terrace. The dessert selection looks delicious and I love the idea of a reserved seat to enjoy the parade sights and sounds!
Anna, I hope this is some helpful advice to continue planning your Halloween Time visit to the Disneyland Resort. If you have any other questions that creep up, please don't hesitate to summon our help by asking another question here at planDisney. We'd love to materialize some happy haunts and spectral suggestions for your upcoming trip!
Wishing you all the frightful delights of the season,
Tishra