Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice.
If you are having regular periods, you have correctly started progesterone tablets
5 days before expected date.
The possible causes of your spotting are:
If you alter the time of intake of tablet, that can lead to spotting.
Better to maintain exact timing and 12 hours gap between the two tablets.
If your periods are irregular, and process of menstruation
already started that can present as spotting.
So, now if your spotting is not getting converted into bleeding, you can continue with your previous schedule.
Hope I have answered your query. Let me know if I can assist you further.