You can take CityBus No.B3,B3A or B3X
But the first bus No.B3 from Tuen Mun Ferry Pier will be leave at 06:10 a.m
The first bus No.B3A from Ming KumLRT station will be leave at 06:15 a.m
The first bus No.B3X from Tuen Mun Town Centre Bus Terminus will be leave at 06:20 a.m
So at 06:00 a.m arrived to 深圳灣口岸 isn't possible
CityBus No.B3 Information:
http://www.nwstbus.com.hk/routes/routeinfo.aspx?intLangID=2&searchtype=1&routenumber=b3&route=B3&routetype=D&company=5
CityBus No.B3A information:
http://www.nwstbus.com.hk/routes/routeinfo.aspx?intLangID=2&searchtype=1&routenumber=b3&route=B3A&routetype=D&company=5
CityBus No.B3X information:
http://www.nwstbus.com.hk/routes/routeinfo.aspx?intLangID=2&searchtype=1&routenumber=b3&route=B3X&routetype=D&company=5
and you can take green minibus No.618
Here is the information:
Get On Point:天恩邨公共交通交匯處,天瑞路(天富苑至天恆邨),濕地公園路,香港濕地公園 / 俊宏軒,天葵路(慧景軒 / 天晴邨至美湖居),天龍路,麗湖居,天城路,嘉湖銀座
圖片參考:
http://www.i-busnet.com/images/mtr_s.gif
/ 天水圍市中心,天華路(天頌苑至天華邨) or 屏夏路
But it is also not possible arrived at 06:00a.m to 深圳灣口岸 because this first minibus from Tin Yan will be leave at 06:00 a.m
Green minibus No.618 information:
http://www.i-busnet.com/minibus/nt/r618.php
Hope above information can help you!