Greetings, Eric! Welcome to planDisney. I'm glad you've brought us your question.
Disneyland Park generally opens at 8:00 AM, and if you are hoping to rope drop or catch an early morning reservation, I highly recommend arriving as soon as the 
parking areas open (one hour before the earliest standard theme park opening) to ensure you aren't late for a very important date. There is not currently a dedicated park entrance for those with advanced dining reservations.  I've found that there tends to be a 15-minute grace period at most restaurants, so if you're running a bit late, you should still be okay within this window. However, I recommend building in more time than you think to make it to your reservations.
Eric, if you're staying at one of the Disneyland Resort Hotels before January 5, 2026, be sure to check and see which theme park has 
early entry, as that may be a tool that can help you arrive at your 
dining reservation on time. Arriving as close to park opening as possible is my favorite way to see the parks. It allows for quick entry to rides and photos with few people in the background!
I hope this answers your question, Eric. If you need any more help, please stop back by. We are happy to help!
See you in the parks,
Melissa