Generally, you'll find that the tutorial is for the previous weeks lecture.
It is really upto you which you prefer...some people like to have a lecture on say, a Tuesday, and then its tutorial on the following Monday, because you've got a whole week to revise, do readings, etc. However, on the other hand, it is also a lot longer to forget stuff.
It shouldn't matter too greatly. Homework assignments for MATH187 are due once a fortnight; plenty of time to ask a friend for help if you're unsure about a question.
Here's a handy little tip, given that the course coordinator organises both lectures and tutorials, they wouldn't run one prior to the lecture in the week if it was impossible to participate in it meaningfully without first attending the lecture
They're well aware you don't have time machines, and wouldn't schedule tutorial classes which they didn't want anyone to sign up for.
Actually, back in first year maths there were a few occasions where a few tutorial questions sprang up that we were yet to cover in lectures. But you can just skip those, nothing you would lose sleep over or anything...