My car will tell me when to change the oil but telling how much percent of "good" oil is left. Sometimes it is by months and other times it is by the mileage and usage of the car before I start getting my reminders. The owners manual will tell you also. So there are several ways to find out. If you don't have an owners manual then you can always look it up on the internet or call the dealership of the that makes your car, if it was bought used. They will tell you for certain. Good luck!
You should read the owner's manual and obey it. But when I get a new car (which isn't all that often) I change oil after the first 500 miles and then go on the scheduled routine. I change my oil every 5000 miles but in a new car you have to go by the manufacturer's schedule to protect your warranty.
It is good to go by the service schedule in the owner's manual. Initially though as you break the new engine in more metal debris will result. I would change it after the first 500 miles, then after the next 2000 miles. After that I would follow the owner's manual recommendation. Also remember to change the filter each time, it is just as important. Be sure to use the correct weight as well (for example, 5w20). Lastly if you find a oil you like stick with that one for the rest of the life of the engine. When you change oil brands as a result of the oil changes , the chemicals in one brand can counter those in the previous brand (you see not all the oil come out when you do an oil change). Your engine gets less protection as a result. See the previous post about the guy who uses Castrol exclusively and has 288k miles on his truck.