Period after failed fet? 😭

Zas

How many days after fet does period come, if it is unsuccessful?

I had my blastocysts transfered on Monday (so today I am 5 days post transfer) and today I had mild cramping, my usual period headache and light brown-ish pink-ish spotting. Am I out? My B-HCG should be next Friday.. please help if you have any experience on that, it was my first ivf round and I am frustrated already 😭