My name is***** and I would like to help answer your question. Provided your dog is not showing any symptoms at this time, close monitoring can be considered. It will usually take 1-3 days for a sock to pass in a bowel movement. Until he passes it, you need to keep a close eye on him- if he has any vomiting, "belching", lethargy/depression, pale gums, bloating, or stops eating, he needs to be seen right away for an xray of the abdomen. You can attempt to give him Pepto Bismol as well to coat the upper gastro-intestinal tract (typically 1 ml per 1 pound; 15 ml = 1 tablespoon). You can also feed a bland diet such as boiled chicken and white rice for the next couple of days to help prevent him from developing gastro-intestinal upset (nausea, diarrhea) from the ingestion. Of course, keep a close eye on his bowel movements and ensure he passes the sock.
I hope this information helps,
Please let me know if you have any additional questions.