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After a little research about the climate of that area of your country, it seems that your years are quite mild. You will be safe to plant now, and you can deadhead as the flowers die off. Phlox will tend to be quite invasive in mild climates, so make sure that whatever is nearby is at no risk of being taken over. As long as what is nearby is taller and more vigorous then there should be no problem.
This collection of articles will give you information about many types of phlox and their care: https://www.gardeningknowhow.com/ornamental/flowers/phlox