Hi,
I am in the opposite situation of you: I left Tonberry in order to go to Gilgamesh. The reason was schedule. If you can manage playing in the morning, it would be fine for you. By experience (and I searched a lot), it is IMPOSSIBLE to find a static on Tonberry outside of evening time in Asia (so betweent 7 PM and 1 AM JP time, roughly). If you cannot play during this time, I think you should go back to Gilgamesh...
Good luck!