There is no easier time to install the faucet than when the sink is removed from the counter top. When the sink is removed you can easily reach the back of the sink, thread the faucet plumbing lines through the sink holes and tighten the faucet to sink. This is something a lot more difficult to do on your back and in cramped quarters if the sink is already installed.
Follow the manufacturer's installation instructions for installing the faucet. Some manufacturers require you to assemble part of the faucet before installing it on the sink. The manufacturer will usually provide you a rubber seal to locate under the base plate of the faucet and the sink.
