Its around 45/60 mins by taxi one idea would be to explore Old Goa, Ponda etc on a morning and then head down to Cavelossim for the afternoon. Or head to Margao which is a terrific (if slightly mad, in a good way) market town and is half way between, then head down to Cavelossim for a relaxing afternoon Benaulim is also a great village/beach to explore down south