Ji Sujit!
There are many colleges that offer you B.Com course in India and hence, the timings and other policies differ from college to college and university to university. Therefore, for knowing the specific timings, you need to provide the name of your college of interest so that I can mention the precise information.
In general, the college timings start from 8.30 a.m to 9.30 a.m and end at around 2 p.m to 3 p.m.
Good Luck!