Way too early to tell and since this is a new route MSP-CUN not enough data is available to develop a trend !The holidays always throw the norm out of the norm.Christmas 2014 falls on a Thursday - The flight if operated on Christmas day should be a good bet.The weekend preceding the holiday iffy. Your plans call for travel on the Monday before Christmas.Check again about 6 months (late June) to see how things are shaping up.Keep checking every week and note the seats remaining either by using Delta.com or the Travel.Net non-rev listing site.Also while on the Travel.Net site check to see if any other non-revs are listed and note the seniority date - the pass class will not known until check-in.It is not likely that a travel agent will book a block of seats during the holidays - but who knows what an affinity group will do.By 90 days out things should start to gel and stabilize to determine if the game is afoot or a bust. Doesn't mean to give up totally.Check the flights the few days before your intended flight and also maybe a day later. Note to see how full those are in case of a dreaded cancellation moving all or some of the passengers onto your flight.If your flight is showing signs of being oversold - rethink about going earlier or later expanding a day or more.OK one or more of you are on revenue holding confirmed reservation tickets - change is out of the question - thus another game changer.Check out the possibility of the non-rev passenger to buy a 20% or more Fly for Less Reservation ticket !?!Have the non-rev pass rider opt to go earlier or later around the road block.Avoid going thru ATL at all costs for holiday travel.My guess if the flight you hold reservations on has at least 5 open seats up and until the day before departure "GO FOR IT" !You are looking for only -1- standby seat ?