I've been working on an iPhone app for about a month and I'm waiting until I finish a key set of features before I put it under version control. I'm making so many big changes that I'd rather not keep track of them all yet. Regular Time Machine backups and archiving a copy of the code after implementing a key feature are the only things I'm doing at this stage.<p>I'm curious though, at what point in a project do you guys normally start using source control management (ie. subversion, git, mercurial)?