Hi welcome to Health care magic forum. You are having regular periods, so both the ways pre pone or post pone are equal in your case. When you take regestrone
for 5 days up to 28th february, there is chance that you can get period between 29th to 3rd of march.
To regulate the flow is used, but the problem is it can be on or after 3rd of march, due to individual variation it could be of any length of time. If it crosses beyond 5th of march you have to take pills for postponement. Of course it may not be true with every one.
Any how don't worry every thing will be fine. Thanks for calling.