You better ask this question to adult webmasters who put a warning message on their homepage which asks a user to enter if he is 18+ or leave the site if he is not!
I have google set as my home page and then I go to whatever I have switched on to do if working or check the sport and news at the BBC if I have spare time
I always open Google first before anything else. Then google mail follows afterwards as there are very important messages that cannot be missed.
First thing i see is google, from there i check my Email (gmail & hotmail), then go to 3 forums i regularly visit, from there its all Facebook