"It has been very frustrating being injured, especially picking up an injury in the last club game before the 6 Nations starts. I trained last week, and this week has been fine," said Jones, who will be making his first start of the 2003 championship.
"Fortunately, it was a clean break to my thumb. Had it been displaced, then I would have been looking at an operation and a longer period out of the game.
The stand-off, who watched the defeat against England from the stands, felt the loss more keenly because he had no influence over the outcome.
"Italy was a bad loss from our point of view, but I found the defeat against England harder to take because I was there in the stadium," said Jones, who will be winning his 26th cap against Scotland.
"I felt isolated, the atmosphere was superb and the boys played so well that I just wanted to be out there.
With Scotland also winless from their first two outings, Jones says there is no danger anyone underestimating the importance of the encounter.
He said: "It is a must-win game for both teams, it is as simple as that. From our perspective, we are ranked ninth in the world at the moment, and if we want to start climbing the ladder then these are the type of games we have got to look to win."