One of the restrictions on your privileges is that you may not send a student on his first solo by day or by night or his first solo cross country by day or by night so none of these flights will count towards your 25. In every other case, you must be 'supervised' by a nominated FI but there is no explanation anywhere of what that means.
Under EASA rules the procedure for the supervision of FIs with restricted privileges should be included in the ATO's management system documentation and approved by the competent authority.