Apr 11, 2014 - 03:06 PM
If you purchase your ticket it is good for you to use any day from today to 2 months from today on the route that you purchased - say Florence to Pisa for example. So you can use that ticket at any time for any day. You first need to print out the ticket, you would validate the ticket but only just before you take the train. If you print the ticket and validate it and don't use it, you would need to purchase a new ticket as once a ticket is validated it must be used within 4 hours.
I hope this helps.