Daniel may have told HKS that he wanted to see his mom and Dannielynn first and then they would think about eating.
You raise many good questions.
I guess my thoughts are: What would I ask Daniel when he got off the plane? How was your flight? I know you don't like to fly. Did you eat? We can stop on the way to the hospital, if you are.
I'm under the impression that HKS wasn't quite that friendly to Daniel.
The idea that "Daniel said he was suddenly tired and Howard saying that he should have made more of it at the time" is a ridiculous response from Howard. It wasn't noon. It was late at night.
The fact that Howard took Anna/Baby/Daniel picture within a couple hours of his arrival showing them all "Alive and Well" suggests pre-meditated "Murder for money". This is the young man who had he lived for 5 more months, would have put Howard "Out of Business".
I'd say that the plot began as soon as Anna found out she was pregnant and he knew that it was Larry's.
He had to get rid of Daniel and Anna...and in that order. Larry didn't have to be dead...just kept away from Anna. After all, and according to Howard's OWN testimony, "Under the Laws of the Bahamas, I am the father".