There is no set time that the workout plan will automatically change - it changes when you want it to change! As long as you are still progressing and enjoying your workout plan, it is not fully necessary to change it.
However, if you want to change your plan, we can recommend that you change it every 8-12 weeks. But again, if you are still progressing and enjoy some of the exercises, you don’t have to change everything. You can always use the exercise alternative function to swap out exercises that you’re getting tired with or not progressing as well with.