Question: How much of the original soil from a succulent pot should I remove when replanting?

When I buy a succulent it comes in a little plastic pot. When I transfer the succulent to a planter, how much of that dirt mass should I move along with the plant? I have done my research and gotten help on this board, and I have a 50/50 mix of succulent soil and perlite ready to go. However, the soil that comes with the plant seems like regular dirt. Will I damage the roots by trying to break away the existing dirt?