Don't worry about it. It's not like WDW where people are beating down the doors to get a table. Just call or go to the website whenever in the day is convenient.
If you call the hotel directly at midnight Pacific time, you can book your reservations with the front desk staff. 1-808-674-6200
I agree with @CaptainAmerica, you don't need to stress out about Aulani reservations. The only time I found it necessary to bust out my WDW dining reservations strategies was when the character breakfast reopened this past summer.
The luau is run by a third party and can be booked several months in advance.
It used to be 180 days but now it's 30 days from the date you wish to dine (Makahiki only right now since Ama Ama is still closed). Ka Wa A Luau can be booked 180 days prior.