The Instructor Development Course and EFR instructor course is run over 11 days. It is immediately followed by the PADI instructor exam in West Bay, Roatan. If you are not doing the divemaster internship with us before the IDC, planning to arrive 4-7 days before the course start date will allow you to do some dives and acclimatize before the course starts. You should not book a return flight until the Saturday after the IE at the earliest. Giving yourself a few days after the IE to relax and perhaps do some specialty instructor training is a good idea if you have the time. The prep course is optional and focuses on preparing you for the written exams it always starts the Thursday before the IDC.