Our app only works if you start timeshifting before your first departure. We make an assumption of where your circadian clock's reference point (x-point) is based on your normal sleep pattern and the chronotype you have entered. And then based on that x point we calculate recommendations for exactly when to see light, avoid light, sleep, etc.
If you already departed, we don't know what happened since you left the natural light/dark cycle of your previous destination. We don't know how and when you have been exposed to light, how you have slept, taken melatonin etc. Those activities have a big influence on your circadian clock. It can go in both directions. Either you have shifted towards or away from your new destination time zone. We therefore don't know where you x-point is anymore. And can therefore not provide you with valid recommendations.
Sorry for the long explanation. I just thought it was good for you to know why it doesn't make a lot of sense to start a jet lag plan in the middle of your travel plan. If you have further questions, please reach out through the chat-support in the app.