Ask the person two years ahead of you. They still remember exactly where the potholes are.

Someone slightly ahead is often more useful than someone far ahead. They remember the specific difficulties because they were dealing with them recently, and they have not yet smoothed the account into something general and inspiring. The details are still available to them.

Find the person two or three years further along and ask narrow questions. What went wrong, what you would skip, what nobody mentions. Specific answers save months, and most people are glad to be asked.