cape's right...my subject tutes fill extremely fast, usually starting with the tute straight after the lecture and continuing on to the later tutes etc. Though if you don't get in to the one you want, it is worth showing up to the one you prefer to see if they can squeeze you in. Usually, and this was the case for all my subjects last year there were a lot of people who didn't make it into any of the tutes, so they had to be accommodated for somewhere. It's worth a try because you really can't help having to work. So my advice is to check as soon as you can after you get home and if the ones you want are full see what you can manage first week, usually they are pretty nice with helping you sort something out.