There are so many variables with different concentrates, juices and climatic conditions, that it is almost impossible to assess the length of time many wines take to ferment.
During winter months, keeping the correct fermentation temperature becomes more important. A table wine should take 4-6 weeks to ferment, however, it could take less or even longer and it is not easy to be specific.
It is always best to use a heater to ensure an even fermentation temperature throughout the process.
Dessert and aperitif wines normally take longer because of the higher alcohol level requirements.