To be honest, I don't have a clue how the limit works. I imagine that it's only in place so that people don't try to include work they did ages ago ("I did an 'Own a Pony Day' when I was nine! Give me a place on the course!"). I think it also helps to make it a bit fairer on people who don't come from an animal-y background or who only recently decided which course they wanted to apply for ("I grew up on a dairy farm, I've owned dogs and cats all my life, as well as a horse for ten years. My dad is a vet, so I've been going there for six years. I also have my own dog walking business and have worked at every kennel within a two hour drive of my home. In my free time I breed rabbits. Give me a place on the course!")
I assume that most people on the thread, including myself, are counting their total WEx, not just what they've done since October. I don't even know if two years is the limit, maybe it's three, maybe it's four, maybe there isn't one; I imagine it varies between universities. When applying I'd mention anything seen, regardless of when it was (unless told otherwise, of course). You'll probably have to put down dates, and you have actually been to placements so it's not like you'd be lying, trying to tell them that you have more WEx than you really do. If they count it, they count it. If not, then you haven't lost anything.
All most WEx is great anyway. You have seen plenty of fascinating things already. You've probably seen some procedures that even 2013 apps haven't. I imagine that at interviews you'll be asked about more recent placements, but still, the stuff you're doing now will really help to set you apart from the rest!
So, to attempt to answer your questions; I have no idea whether or not WEx from before October 2012 it will count for the 2015 apps when it comes to application time, but if I compare what I've done in total to everyone else's totals then I'm way behind
.You won't be wasting your time at all, quantity of placements is one thing, quality is equally, if not more, important. Hopefully this summer you'll see some interesting things, and if you're lucky you'll be able to nab some more contacts for later.
What was your dad at the vet for? And does your friend want to be a vet too?
Sorry for the extreme wall of text! I tend to ramble on a bit... hopefully it all makes sense. Anyway, I'm not sure how often I'll be able to get online until June because of exams and such, so in case I'm not back until then I wanted to wish everyone on this brilliant thread the best of luck for any exams they may be taking. You're all intelligent people, you'll be fine. Do yourselves proud.