What is the first day of missed period?

[Rmar]

I have read it on the instructions of lots of hpts and I can never figure out which is the first day of missed period. Is that the day AF is due to come or the day after?

 

[immimx]

i always assume its the day after... but now you got me thinking!

 

[Rmar]

It seems like it should be simple but, to me, it could mean either! Lol.

 

[camerashy]

i take it as the day after af is due

 

[cakecustard]

I always class it as the day after because my AF can show anytime on day 1 x