Why You Can't Make an Older Student

As a new member of Hogwarts, you may want to create a student that is superior to the other members of Hogwarts. Understandable, but it is not allowed in this guild.

Why?

The reason why we don't allow new members to create older than 11-year-old first years is because you don't know the inner workings of the guild yet. You just joined. You need to get used to how the guild works. How can you hope to be a student at Hogwarts when you don't know how?

So, once I get used to the workings, what year can I go up to?

The highest point you can jump up (after being in the guild for quite a while as a student), is a third year. Any year after that is a headache for both the crew and you as the student character (it's because of electives).