The plant is opportunistic and will grow any time of year when the conditions are right. If you are having problems with wet roots during repotting, wait until the soil is dry before you repot. Normally I wait until the soil is mostly dry before repotting anything. Doing this also helps serve as a way to independently confirm my guesswork regarding how fast the soil is drying out. I would use regular potting soil cut with about 50% pumice, which is the same thing I would use for cacti.
There is no such thing as too much summer sun for this plant in a mild climate. What are conditions like where you are?
