I am assuming there is one big NOT missing from this sentence.
San Miguel de Lillo and Santa María de Naranco are two of the most beautiful pre-romanesque (i.e., 9th century!) buildings on any camino.
Depending on your walking distances, Oviedo - Naranco- Grado is certainly doable, but the Naranco sites only open at 9:30 in summer and 10:00 from October through March. That would make for a late arrival. (And I believe all is closed now because of Covid, so you would need to check on reopenings when you actually get there).
If you are coming from across many oceans and taking a jet lag day in Oviedo before stopping, walking up and back to the churches is a great way to get some daylight so your body can acclimate and you also get a bit of hill walking to prepare you for what’s to come on the Primitivo. From the Oviedo train station, it’s 3 kms up through pretty residential neighborhoods to the sites. You can also get a municipal bus but why waste the opportunity to walk?!
Another option is, as Tinca suggests, to make day 1’s destination Escamplero so you will have plenty of time.
The San Miguel de Lillo church was closed for two years while restoration work was underway, so it must be truly amazing now!