After 10 minutes only:
Once caffeine enters your body, your heart beats will increase, and your blood pressure will increase.
After 20 minutes:
Start focusing, make decisions easier, and feel less tired.
After 30 minutes:
Your body will start to release adrenaline.
After 40 minutes:
The level of serotonin will increase in your body , which will enhance the performance of neurons and motors.
After 4 hours:
Your body will start burning fats even with absence of your movement and activity.
So enjoy your cup of coffee..