Introducing new technologies into a software development process or project often produces both good and bad effects. If it is well planned it will improve both productivity and quality. We present an incremental development process planning approach (IDPA) which uses the idea of technical dependency-based assessment of the project planning for a small and stable development team shifting slowly but steadily to a new software paradigm that fits the traditional development process. The project plan was a well-connected set of incremental fragments of improvements with the introduction of new technologies or methods to the previous plans. IDPA is a method of assessing each technology or method to be decomposed and scheduled according to the technical dependency at the time of introduction. We also present a case study applying this idea to a real development project, in which object-oriented technology and the cleanroom method were introduced, and present the results of its evaluation.