If you think you aren?t able to test before a couple of days of work have been completed, then you really aren?t trying very hard. Re-order the tasks. Introduce a cut-down version of a feature that will allow you to stop at that point and ensure things are working okay. It is rarely necessary for an application to be ?in pieces on the floor? for any significant length of time (>2 days) in an unworking state.
Nerd Herding for Beginners