Sleeping and feeding

So my 2 week old has had a few nights where he is up 5 to 7 hrs with maybe 10 min of sleep at a time. I told his doc and she said to only feed him an oz at a time to keep him up. So yesterday I did that and I was able to keep him up 3 hrs before he refused to stay awake. So my question is how long should I be keeping him up during the day..bc I knw he still needs to sleep.