ASAP means that you will get whatever traffic your bid could win you at any given moment. Meaning, you could reach your daily budget within minutes or hours, it just depends on how high your bid is.
If you want your traffic to be distributed evenly per hour throughout the day, it’s best to choose an Evenly budget type. For example, if your daily budget is $24, that means that you will get maximum traffic worth $1 per hour and not more than that. So basically it’s your daily budget divided by 24.