I have no internal "schedules" whatsoever, and next to no sense of time, too. I seem to be trapped in the current moment. It's odd, really - I may be very careful and give a lot of thought to what I'm going to do, but no matter how hard I try I'm still likely not to do it on time.
That is why making a written schedule, or one on my mobile phone, is very important. It gives me some signposts according to which I can structure my time, and this is still something, even if I have no subjective sense of them and they remain just figures on a sheet of paper. At least my days become organized in *some* sort of way.