Hi Jason
You can get a list of Users' first access to Moodle by using browse list of users and then adding a filter with the appropriate dates. (I know that is not exactly the same as the date created, but it might be a start!)
There are some wizards here who may know a simpler trick, but the best way to do this is probably going to be by doing an SQL query on the database. If you just need names or basic profile information, then it's not too difficult - it depends on how much you need in your report!