I understand that the plot twist in the last chapter is CRAZY CONFUSING so I decided to add a little explanation.

So, as you know, this is a repeating process of going back in time, trying to save Sylvia but failing and informing the next generation on how to do it properly.
There is one circuit where Erza doesn't take the job that killed her. Her son (who is the ten year old Jellal you've seen so far) goes back in time to try and save Sylvia (who dies saving Juvia) but he tells the young Erza to take the job. That young Erza indeed takes the job, but dies.
The Jellal who told her to take it, instead of going back to his own time, travels back to just before he left, in the hope that sacrificing himself will be able to solve the paradox.
This is where he joins the main group. When he arrives, he goes to his own house, locks away the Jellal from that circuit and travels through time along with the group.
So he is technically not from the same time as the main group, however pretends to be until he is exposed in Chapter 6. However because he used the magic in a time that was not his own, he is unable to return to his origional time, he can only move forward, to new cycles (well technically backwards but even I'm confused now so) and will continue to do so until the issue is solved, or he dies.

If you understood, don't worry I am not doubting your ability to work things out I am simply clearing up for mistakes on my part. I was not clear enough and the least I can do is try to explain fully.

;)