In my experience the best way to juggle freelancing and a startup is a to have at least one person who is only doing work on the startup. Additional people can

In my experience the best way to juggle freelancing and a startup is a to have at least one person who is only doing work on the startup. Additional people can split their time between the startup and freelancing but you need one person who is 100% dedicated to the startup. That of course means you need 2 or more people involved. Enforce this to the point where the person/people doing freelance work don't discuss it while the dedicated startup person is in the room. This ensures the startup is always moving ahead no matter how much freelance work is happening and that you have at least one person whose headspace isn't cluttered with freelance billing, deadlines etc. Even just knowing about a freelance project that is behind schedule or about a difficult client is a drain on the startup so keep it contained.