It depends on the type of ticket that you purchased.
Sometimes online ticket brokers will sell tickets that are somewhat cheaper than normal, but they may have an expiration date. I don't think these are as common anymore now that MYW has been around for a while, but I know that they were still availible online occasionally about a year ago.
As long as they are Magic Your Way tickets, they are ready to be used at anytime. Today, tomorrow, two years from now, it doesn't matter - but the FIRST time you use them it starts the ticking clock for 14 days from the first use, after which the ticket expires unless it has, or you upgrade to the No Expiration option.