hi,

see in case you want to do full time post graduate course, your classes timing will be 10 a.m -5 pm, for part time courses timing will be 6-9 p.m , this is the basic timing which most of the colleges follows. however it may differ with college wise. now a days there is many university or institute offers online learning option which is self paced and you may continue doing it with professional working. you have to contact with college authority to know exact details of  the class timing .