for some time I was all the time trying to identify who-did-what as you mentioned... looking at archives or old pictures is really a good point, and not only from the older labels (you'll see how much some collections resemble from one year to another, even if it's just the make up, the hairstyle, the way a jacket is cut.... the little details!)
HOWEVER, and I tell you this because i've been through it (
B)), i am 100% positive you won't have to do too much of an effort... it just comes naturally!! you spend your time at tFS (you needn't study it or memorizing) and you'll find yourself looking at the "stars wear runway looks" thread and saying I'VE SEEN THIS! and you'll remember the label, the season, and maybe the model who was wearing it on the runway, and what her make up looked like
...or maybe you'll be in the streets and you'll tell your friend "that's a Christian Lacroix skirt, from a couple of seasons ago", and he/she (in case he/she is not a devoted tFS) will tell you... "how do you know that? it's just a skirt!!"
whatever!! random thoughts and personal experiences
the best advice i can give you: don't EVER log out from the Fashion Spot! (i try not to)
WELCOME TO THE FASHION SPOT!
EDIT: i forgot to say... you will know you've acquainted the identifying skill, when walk by a Zara window and find out they don't just copy some of the looks as you had heard... BUT ALL OF THEM!