World test champions New Zealand will play white ball cricket against the Netherlands late next month but Williamson said eschewing a likely return date remained part of the treatment strategy this time.
"It's improving, it's been a bit of a long slog," he said.
"Hopefully this time gives it gets what it needs, it will be nice to put it behind me.
"It does seem to be progressing quite well - in last small period my batting load has started to increase quite a bit more, it's looking positive."
Williamson expects South Africa to be a far tougher proposition as the two sides return to Hagley Oval.
"We couldn't have hoped for much better [in the first test]," he said.
"Everybody bowled beautifully, there were a number of great contributions with the bat and we caught everything - it was one of those days.
"I very much think South Africa will be better for the outing."