To maximize time, just take a blue taxi straight from airport to Tai O. I suspect about HK$150. Not unreasonable. When you get there, check the time of Bus #21 to Ngong Ping (it's infrequent), and allocate time you spend in Tai O. [Taxis may not be readily available.]

It's about 20 minutes to get to Ngong Ping. After Big Buddha, take cable car DOWN to Tung Chung. It's less likely there'll be lines going down. Unless it's Sunday or Public Holiday.

From Tung Chung, either take S1 bus (takes about 15 minutes), or blue taxi back to airport - cheap 5 minute ride.