I know there is some disagreement on how long to leave in the original oil. Perhaps out of ignorance or otherwise, I tend to favor the camp that says change it early.

My ride is an '06 Accord with around 800 miles, and we're getting ready to go on a 2000 mile trip. I stopped by the dealer asking about buying the same type of oil that comes in the car, but the service mgr said they don't have any. He recommended leaving the original oil in there for at least 3700 miles, and preferably the full 5000 miles. My plan was to keep the same type of oil in there for the first 5000 miles, but have it changed midterm.

Is whatever Honda uses as its initial break-in oil available for sale someplace? Or am I foolish for worrying about it?

 

It's a high moly content oil that is exclusive to the factory. I couldn't stand it and changed mine to Mobil 1 (0W20) around 3200 miles, since then it has yet to use any oil but did during break in.
Any dino 5W20 will do just fine for top offs during the break in period. If you want to continue with a high moly oil like what's in it use Havoline 5W20. The Honda brand name oil is high in moly but likewise in price.