pregnant 10 days after period

Maryam • first time momma

my cousin had a very strong feeling she was pregnant literally 10 days after her period had finished

no one believed her as it would be very early to tell

but one day after missed period she got a very dark line indicating she’s pregnant

sadly she miscarried but my point is is it possible to tell 10 days after period if your pregnant and if so who has experienced that?