Cheapest way to reach goa(thivim) from navi mumbai airport?

hello!

im planning to visit goa in the first week of april. since flights to navi mumbai are cheap, we are wondering if we can take a flight to navi mumbai and go from there to thivim either by train or by cab (bus is less preffered)

from what i could find, the closest stations are vashi and panvel but i couldn't find available trains in the afternoon/evening. please help me out