Most of H store do the same thing. They did not discuss inventory over the phone since it's always changing unless you're a local customer. As local customer, you can just drive and be at the store and buy the inventory they have the very same day. If you are VIP that's a different story

Regarding delivery, most of H store that I ever went to, they stated they get delivery once a week, at certain Maison may be more. So yes, when you came at the right time you can get a lot of stuff in your wish list. I was offered KC just as walk in and no need to buy anything. While in my local store my SA said that I have to buy different stuff from different department to get one..go figure. LoL
Now, the H craftmans are off in August so it will affect how much and what they will get for all H stores. I think they have to rations the inventory

)
I would book the ticket for the purpose of vacation and who knows you may get a surprise for H Hawaii.
Have fun in the sun!!
PS I've never had bad experience at both stores, although I've been reading some bad experience here lately.