When flying from Brisbane to Kazan, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
When travelling, it's generally smart to pack in preparation for rain or any other conditions that may arise. The rainfall in Brisbane is roughly greater than that of Kazan. You can assume this to be the case over the next 13 days.
Expect the weather to be around 29 °C on average in January. As the temperature peaks, try to get your plans done early, as flight price and availability will have an impact on your travels. The climate in Kazan is generally colder than in Brisbane.