The dialog for starting a gig or date normally will not include a bonus:


To qualify for a bonus, you need to accumulate enough Gold Stars (for gigs) or Gold Hearts (for dates).  To see how many Gold Stars or Gold Hearts you have vs. how many are needed, check the lower left of your screen.   

In the example below, the player has 853 gold stars out of 999 needed, so will notsee the bonus available:

Once you have accumulated the needed amount, you will see the gig display a bonus available: