The money beyond your initial team comes from your background (PHB pp, 125-14.Are you playing 5e? The PHB tells you how much they start with, depending on class and background. Classes, by default, start with equipment, not cash. I recommend continuing this for new players. The backgrounds have some objects, and always some gold.
The official rules are that you can choose between a random amount of starting gold or starting gold and the equipment of your environment and class. In other words, any gold or equipment gain from using the TIYL tables adds to standard methods for determining starting gold and equipment. So how much gold do you start with in d%26d? In 5E Starting Gold by Level - Levels 2+; depending on character level 17 or higher. When you're finished buying the equipment, the rest of the gold you've drawn becomes your starting gold (and silver and copper, to the extent that you have a smaller change left).
Usually, in the fifth edition, rolling for starting gold is a bet that is not mathematically wise, but there are some exceptions and occasions when it is better for you to roll for your gold. For whatever reason, the bard class on average gets more gold when rolling than their starter pack is worth, usually around 25 pieces of gold.