He anticipates being out of action for a little under three months in total but is hopeful of heading to South Africa even if he doesn't make it back in time for any of the Scarlets' remaining six fixtures in the RaboDirect PRO12.
"I have had the sling off this week and now it is a case of working with the physios to try to get the full movement back in the shoulder," Williams told the South Wales Evening Post.
"It is a 12-week timescale from my operation so that takes me to the Blues game - the final match of the season.
"If everything goes well hopefully I will get some game-time, but if it is not quite right then I am not going to risk coming back just for half an hour or 40 minutes. The South Africa tour is five weeks after that game so that does give me a bit of time to get back to full fitness."
Injury came at a typically-frustrating time for the 23-year-old given that he was in possession of the No13 shirt for his country and was looking to kick on having regularly been used as a replacement in much of his international career to date.
With fellow Scarlet Jonathan Davies out of action with a pectoral problem, Williams was all set to build an impressive partnership with Jamie Roberts before a huge hit on Brian O'Driscoll robbed him of that chance with just 16 minutes played at the Aviva Stadium.
"I have had plenty of 'stingers' before but this felt completely different. I tried to keep going but it was clear I couldn't carry on," added Williams, who knows he still has plenty of time to ensure he is a key part of Warren Gatland's squad for next year's Rugby World Cup.
"It was really frustrating. With Jon out I had a chance to play a few games and I was happy with the way things were going. These things come with the job, but there are no regrets about what I did, it is just unfortunate.
"There is going to be a lot of rugby played over the next 16 months or so. It is important that we get two or three players in each position who can do a job so that Warren has a strong squad building to the World Cup. There are two Tests in South Africa this summer, four autumn internationals, another Six Nations campaign, and a lot can happen in that time."