Our company likes to hire new developers, with no experience. We have a core set of skills that we try to get them up to speed with, like ASP.NET and WinForms - to teach basic programming, the .NET languages, and the things they'll need to maintain and write. We also try and mentor them through early projects, so they can learn from someone more experienced.

Recently, we've been seeing the benefits of new frameworks like MVC and ideas like Unit Testing and TDD (by extension, dependancy injection and IoC), and we'd like to start using these in the team. However, this increases the time that a junior would have before they can get started on a new project - because doing something like unit tests wrong could cause major headaches months or years later in maintenance, especially if we believe unit tests to be comprehensive.

How do you handle the huge amount of things that a junior will need to take on, acknowledging that the business wants them working independantly as soon as possible? Is it acceptable to tell them not to unit test till a while after they are independant (and give them small, simpler projects in the meantime) before taking them to 'level 2' of the core skills?