cohost

Hi @tessmck 

Unfortunately, there is no mechanism to make the first attende a special role. If you were to assign someone to be alternative host, then when that user joins, thy are automatically assigned host controls, even if they are first or last to join the meeting. Just be aware that using alternative host requires you and the other user to both be licensed users and on the same account. 

Hope that helps and please make sure to mark the solution as accepted if this information is what you needed.