The Grove based team announced on Thursday that Stroll will race for them in 2017. The young Canadian recently won the Formula Three championship by 187 points.
"It will obviously be Lance’s rookie year in Formula 1 and as much as we are doing a lot of work behind the scenes at the moment to make sure he is as prepared as possible, going into Melbourne next year it is going to be an eye-opener," Williams said.
"We have noticed in a short term with Lance he is so capable, extremely intelligent and he puts the work in. The one thing I have learnt about Lance over the 12 months we’ve been working closely with him is his work ethic is second to none for a 18-year- old to achieve what he has in such a short space of time.
Williams pointed out that it is almost certain that he will make mistakes in his rookie year but thinks he will learn from them quickly.
"I have a huge amount of confidence that when he gets into the cockpit in Melbourne he can deliver but he will need some time like any rookie does in this sport to bed in.
"There may be some mistakes but that is going to be an inevitability, but we already know from Lance that he learns from his mistakes quickly."
Bahrain International Circuit - Winter testing