The Australian took over from Ian McGeechan after last year's World Cup but has not had the chance to test his new-look squad in competitive action since.
That means the trip to Cardiff's Millennium Stadium presents Williams with a daunting opening to his reign as national team boss, which has already seen him adopt a radical approach to overhauling the game in Scotland.
Williams has included three uncapped players in his first RBS 6 Nations team - in Edinburgh centre Tom Philip, Borders scrum-half Chris Cusiter and Edinburgh back-row forward Allister Hogg.
The former New South Wales coach concedes he will have no indication of how much progress the Scots have made under his guidance until kick-off.
"The difficulty on the international stage when you make changes in playing and coaching personnel is that you do not have any form on the board," reflected Williams.
"You do not have any evidence to make your assumptions apart from the training field, and that's different from the playing field."
Williams is nonetheless determined to savour every moment.
"It's such a wonderful occasion for me to be at the Millennium Stadium," he said.
"As a young boy in Australia, Wales were our idols. It was Wales that kept things going in the early 1970s.
"Sometimes Australia had no internationals for years; no one toured, and the Australian international side wasn't very good - they were beaten by Tonga in 1973.
"We used to look up to the Welsh side and watch matches with Bill McLaren commentating."
Williams admits Wales will be favourites because of their Rugby World Cup performances against New Zealand and England.
"Talk is cheap, but it is right they are favourites," he added.
"But I have been the coach when we've been huge underdogs and huge favourites, and it doesn't worry me.
"Wales have been together for a long time and they are reaping the benefits of the hard work. That gives us great heart, because they have been proving that if you do the work you get the benefits.
"They saw the benefit in the World Cup against the All Blacks and England, and I assume they will want to make another step forward on those performances."