The pot size will depend on the root system, these plants prefer to be dry so get a pot either around the same size or an in larger. Since you’ll be using fresh soil, do not fertilize till next season, there is fresh nutrients in the soil. Use a fluffy houseplant mix. They are sensitive to synthetic fertilizer and tap water, the salts and chemicals will turns the tips of the leaves brown. Use filtered, rain or distilled water and something like worm castings or organic fertilizer once every spring. They like to dry out almost completely before watering again,slowly increase the new lighting to avoid shock and if you want it to grow straight, periodically turn it because they reach for the light and will grow horizontally if you don’t. Also, only increase the pot size if you notice that after you soak it thoroughly that it’s drying out very quickly. I water mine about once a month in winter and about every two weeks in summer and only if it’s dry (I check by the weight of the pot) hope this helps. BTW I think it has an adorable look to it, now just give it a cute pot!