Changing standard Collections to External API Collections

I’m starting to design an app, and envisaged creating test collections to ensure the data structure is correct and everything works, before connecting these to our live data via API.
Are there any issues in changing standard collections to API collections, or do I need to use API collections from the very start ?
If i can do this can you point me to the documentation. I don’t want to design anything and find that i have to start again.

If you’ll be changing your user collection too, you should do it from the beginning.