Normally, when a new user logs into Moodle for the first time and a Moodle account is automatically created, Moodle pulls the user's details from LDAP and stores them in the Moodle user profile according to the LDAP plugin's settings.
When you create a new Moodle user manually on Site Administration -> Users -> Accounts -> Add a new user and want the newly created user to be found by teachers before the user has logged in for the first time, you have to specify all user details in the user creation dialog.
It would be great if you would only need to correctly specify the new user's username (which corresponds to the username in LDAP). All other details like first name or email address could be filled with placeholder content. After you click the "Create user" button, Moodle should pull the other user's details from LDAP and create the user account correctly with the details from LDAP.