This is right time. The rule is the fruits should be harvested before the rainy season. So you can easily add 120 days to the sowing time, if it is not falling under rainy season, then you can cultivate.
Normally the water Melon wil be cultivated in the months of Feb to April .The will be started from April onwards to focusing the hot summer.Otherwise the water melon farmers as well as traders ,platform sellers are heavily affected financially.