While many people find heat to be a warm fuzzy for muscular pain. It should never be used during the first 36 hours of injury.

http://www.uihealthcare.com/topics/prepareemergencies/prep4922.html

Rest
Ice
Compression
Elevation

All top athletes will ice critical performance joints the evening before and post performance/ competition. Your body may not be making the high buck dollars of competitive sports but it's the only body you have this time around. Why not treat yourself as you would want to be professionally cared for? 
For clients who just can't bring themselves to ice old injuries (more than 2 days old) I encourage them to use a 20 minute heat compress to follow up their first icing before icing again. Its referred to as contrast therapy. There is nothing more decadent than entering a hot tub with an ice bag around your tired achy neck...AHHH!!!

REMEMBER!  heat or cold never more than 20 mintes at a time!  You can give yourself frostbite with cold contact directly on the skin as well as crock pot yourself with a forgotten heating pad.