I don’t think there’s day 1 only options that are not available later, other than your rotational dinner which you go to once on the three day of course. I’m not sure if Marcelina closes. It was open when we went other days for breakfast and a quick snack.
The only option on the first day are the market or 1923 for concierge guests. We did not do concierge. The quick service stations/kiosks on deck may have been open but I didn’t check. BBQ was just ok from there, they had pizza (didn’t try it), and we had a nice bowl from the Mexican kiosk. DW said soft whip was good. I’d stick with the market! It was open until 3PM
The market was very good. I didn’t mean to undersell that. There are various walk around food stations that you are served at. Shrimp, salmon, grilled chicken, salad, plant based options, pastries and desserts, Indian, Chinese, etc. There was limited ingredient information. But I’m sure if you asked specifics they’d tell you.
I didn’t adapt to late dining particularly well. I’m an old man who likes his dinner on time

that said, we did Palo two nights and rotation one night. On the last day, we had bbq on the island around 12:30PM, by 5PM I was starving and so I couldn’t have waited. But there’s plenty of good “fill-in” dining…we had good bowls from the quick service that saw us through to dinner. And because of that we’re we’re able to catch the 6PM show and have a drink in a lounge before dinner. It made for a nice, long night that way around.
In case you didn’t know, you will get assigned to a table with other guests for dinner. We only found this out on the last night when we walked into 1923 and were sat with two other couples on a 6 top. They were a nice group, but I don’t think they’d spoken much the other two nights (they left the middle seats unoccupied!). We had fun and talked all night.