http://www.tentonhammer.com/node/67008

My favorite part,


"About 4 weeks before launch is a good time to open the game up to consumers. If you have done your job right, you will know if the game is ready before you open beta. If not, you don’t open it until it is. It doesn’t hurt a company at all to open the game up to players four weeks before launch. It allows them to try before they buy and it allows us to make sure the game holds under pressure as well as providing a rolling launch so day one is not so crowded. "