A bad API can constrain your implementation and often can't be changed once it's in use by loads of users. APIs should be right from day one if possible.
I would add the nuance that the possibility of controlled migration from one versioned API to another should be right from day one, not necessarily the first API version.
A bad API can constrain your implementation and often can't be changed once it's in use by loads of users. APIs should be right from day one if possible.