Final container size and setup
Fifteen to twenty-five gallons is the sweet spot for a single outdoor plant in a short season: big enough to support full-size growth, small enough to manage.
Fabric or plastic
Fabric pots air-prune the roots, which builds a denser, healthier root mass than a solid-sided container of the same size. They also dry out faster, which matters in a wet climate and matters less in a dry one.
When to transplant
After your last frost date plus a buffer, not on the date itself. A late frost still happens more years than not, and a plant in its final container is much harder to bring inside overnight than one still in a nursery pot.
Soil mix
Straight garden soil compacts in a container and drains poorly. Cut it with a quality bagged mix, or use a bagged mix on its own if you don't have reliable garden soil to start from.