Advance booking of the train tickets has its own advantage. If you book your train tickets much prior to your travel date the better chance you have in obtaining a confirmed ticket in the class and in the train that you have desired. If you think of booking your train ticket at the last moment then you will have a very thin chance of getting a confirm train ticket. Even if you manage to get a confirm ticket you may not get it in your desired train or in your desired class.
'''Advance Booking period for long distance train'''
For most of the long distance train you can book train tickets 90 days prior to your date of travel. This 90 days is exclusive of the of the final departure date of the train. So therefore, in total you can book tickets 91 days prior to your travel date.
On the other hand, the tickets of the certain long distance train can be booked either 92, 93 or even 94 days in advance. For instance, the tickets for the Kerala Express (which travels from Jhansi to New Delhi) can be booked 93 days in advance. This is due to the fact that Kerala Express takes almost 2 days to arrive to Jhansi.
'''Advance Booking period for short distance train '''
Certain short distance trains can be booked by the passengers 30 days prior to their final travel date. Again tickets for much shorter distance train can be booked even 30 before its final departure date. These trains are generally daytime trains.