Are these 6 sentences correct?

There was a time when I started studying for exam 15 days before the exam. After that there was a time when I just studied one day before the exam. And then there was an another time when I just studied for about three or four hours in morning before the exam, and now I don't even study for exam. I just... show more There was a time when I started studying for exam 15 days before the exam. After that there was a time when I just studied one day before the exam. And then there was an another time when I just studied for about three or four hours in morning before the exam, and now I don't even study for exam. I just directly go to the school for exam without studying anything. So what I'm saying is actually the evolution of my studying.
Update: Are my sentences grammatically correct?
4 answers 4