Thanks to the increased cap on poetics, it's a decent assumption that having at least i120 going into the expansion will be a good idea. Failing that, getting yourself as geared as possible is your next best bet.

Edit: at minimum, you need to be i90. Stress minimum. It is a bad idea to try to stay as low as possible, as you are forcing others to carry you through story fights and you'll be at a disadvantage in the overworld