Question: I planned on having a prologue and introducing the main character at the end of it. Should I do that or should I wait till the first chapter?Answer:
For a lot of readers, it's important to connect with a main character who they can empathize with right away, preferably on the first page.
Prologues cause problems because they often are the start of the overall throughline (rather than the main character's throughline) and often concern events that take place before the main character enters the story. Sometimes they concern events that happen before the main character is born or when the main character is too young for his/her story to really begin.
In fact, this is why they get labelled "prologues," which literally means "before the story." It's a way of reassuring the reader that the real story hasn't begun yet.
Often it is better to leave out the prologue and simply fill the reader in on what happened later on, either in flashback, memory, or by having the main character find out what happened from someone else.
If that doesn't make sense in your story, I would suggest you introduce the main character at the start of chapter one, because some readers will simply skip the prologue anyway, and you don't want them to skip the introduction of the main character.
Again, this depends on the main character's age when introduced.
For example, in Harry Potter and the Philosopher's Stone
the first chapter is much like a prologue in that it shows events that occur when Harry is a baby -- before the reader begins to see the story through Harry's eyes. The novel begins in Vernon Dursley's point-of-view, and later switches to Dumbledore's.
This is actually a problem for some readers, because it is quite a few pages before Harry is introduced. Harry's story doesn't really begin until he is 11 years old.
At the same time, Rowling was wise enough not to show Voldemort's attack on the Potter family, which would have made a more lengthy prologue. Instead, the reader finds out about the event later when Harry does. Omitting this event creates a little mystery which helps pull the reader into the story. Like Vernon, the reader wonders what all these oddly dressed people could have been celebrating the day before the infant Harry arrives on the doorstep.