This is a post by Mark Hindsbo on PTC site.
One question on the minds of many product designers is: “When in the product development cycle should I start using simulation?”
The answer is simple. As soon as you have an initial concept it’s time to start simulating. The earlier simulation is brought into the development cycle, the earlier you can identify which concepts and design paths are best.
Around 80 percent of development costs are committed in the early design phases, so it is important to start narrowing down these design paths as soon as possible. Additionally, changes later in development can be 20- to 100-times more expensive.