Start off by cleaning your cabinet, removing any dust. Lay down the vanity top with its polished surface down on the cabinet. Level it from the front and the sides. Use shims to maintain level if needed. Do a trial fit to check if the measurements are correct. Then place the sink bottoms up in the sink hole. Ensure that the edges are all aligned. Make sure that the sink holes are fully covered and check with your fingers if a uniform edge forms around the sink.
With a marking pen, draw the border of the sink around it. Add another two lines on the back and front of the vanity. This will help you in gluing the top. After the glue has been applied, place the bowl cautiously, maintaining the center with the guidance of the drawn lines. When the sink is in place, make a water tight seal by applying silicon to the rim. Leave it to dry and set in its place.
Apply silicon on the sides of the vanity and carefully put the vanity on the cabinet. Help of another person will make it easier. With the help of a measure, align it according to dimensions. Usually tops are made 1/2 inch extended on the sides. Erase the extra adhesive and let it dry. Then put the splashes in place and check if they fit. Apply adhesive to the side that is unpolished. After you have fitted all the splashes, apply silicon to the joint. Likewise apply adhesive on the remaining faucets, use a sponge to clean the excess and let it dry.