I'd install a basic helpdesk tool right away. Some are free, others are just a few hundred dollars.
Customers don't always inquire in a linear way and once you've got more than one person on, managing their emails, viewing their history and communicating the same message becomes essential. Furthermore people come and go [on your team] and people take time off even if they don't go. Support makes businesses -- and breaks them -- so while it may take a little work to get going, it's really not an option.