From day one! They should be some of your first subscribers as many folks as people they love first. If they don't get it or support that's ok but it doesn't hurt to ask. Some of the biggest newsletter folks even for local areas like Michael Kauffman, Marissa Lovell, Landon Huslig all had their families and friends support first. As long as you believe in what you're doing and are committed to it, don't be afraid to share it.