When did Snape invent his curses?

[leavingedenbehind]

No: HPFGUIDX 133338

Juli: He could have invented them long before his 6th year, but only 
> during his 6th year he wrote them on his Advances Potions Book; or 
> since he seems like a natural potion-maker, he could have been 
> studying on his own, just like HArry has studied DADA all by himself 
> (and Ron and HErmione, of course)


Additionally, the theory that I've been reading a lot on the boards is that the book was 
actually Snape's mother's book when she was at Hogwarts, and if we accept this, then it's 
not a stretch at all to assume he had access to the book before his sixth year.  Also, 
enlightened by Dumbledore's revelation that only the source of magic is traceable, not the 
caster, for the purposes of underage magic detection, we may be able to infer that Snape 
may have had the opportunity to practice and hone his skills, far ahead of his class, at 
home during holidays.

Amanda