I like to change out my fluids/filters on new equipment after some short break in cycle. That is dependent upon things like environment, loads, mileage, etc. Anywhere from 500 miles to perhaps 1.5k miles. I will then balance the next OCI out to where the first "normal interval" would be.
Example: OEM OCIs at 5k miles. First O/FCI at 1k miles, then 4k miles later, then every 5k miles. Keeps me at the OEM increments.
I presume you're posting in the HDEO looking for some miracle fluid that does not exist in the PCMOs? If you're going to follow the OEM OCI guide, then just pick a quality brand name PCMO within grade and be happy. The Hemi isn't known for any lube related deficiencies that I'm aware of. Stick to OEM for warranty purposes.
Welcome to the site, BTW!