The Gambling Dan is not recommended at any time. It's only 1/3 chance of getting the Queen. Unless your lucky, you'll win. If unlucky, you'll lose your money. Even your bank.
Tips:
Double the money if you have lost.
$100-$200
$200-$400
$400-$800
etc.
The higher the money, the better chance of winning. Also a chance of losing.

The gambling dan is a slow way of earning money. Especially if you are losing and winning at the same time. I suggest you to go looting instead of playing gambling. Unless you're super duper lucky to win $100,000.

Here is a video on Gambling Dan. The guy says that if the Queen is in the middle, which ever way it goes is the right one. (But I never tried this so don't comment on this video).