in reply to Developing larger applications.

Source control. But if you are starting from scratch forget CVS and use subversion or arch.

Try to get, and keep something working. If 3 months arrives and you have nothing to show you're screwed. If it works, but lacks all the planned features (even important ones) you have a chance to explain.

3 months is not very long, particularly if you have other responsibilities.*

... insert all advice from above posts here ...

qq

* I read, I believe on perlmonks, some sage advice about how best to respond when the PHB asks if you can 'just quickly do ...'. The best answer is 'Of course, what would you like me to postpone?'