As a general rule it is 4 meals a day but don't panic if it won't eat 4 times, my youngest German Shepherd at 8 weeks would only eat 3 meals a day, I couldn't persuade her otherwise, just so long as puppy is getting enough food for his age, if you are feeding a complete diet, follow the guidelines on the side of the bag/can, remember these are guidelines only, if you think pup needs a bit more then give it and if pup doesn't clear up at each feed ( though with a Lab I doubt that will be a problem!) don't give quite so much.
Good luck with your new puppy.