Just rechecked my email, there it was, as you said, in the small print. Thanks for that.
Lately with mine they don't put the times in the main text section, only in small print of the email. Every time without fail, it's for D+3 - i.e. if I get it on Sunday, offer is valid Mon-Wed.
I suspect there's a large amount of people expecting points from the day they get it, only for them to never come.