Multi-lingual environment
Chapter 18, which deals with APEX Globalization, specifically claims that multi-lingual support can be added in any phase of the development process. We are not taking it back, of course, but if you know in advance that you are going to develop a multi-lingual application, it would be wise of you to start planning it right from the start and not wait for the primary language development to end. Using translatable supported components, such as shortcut (the message type), defining Globalization parameters and validations (e.g. date format, local currency, etc.), and taking translation into account in your external JavaScript code can save you a lot of time and effort when you reach the translation phase.