It's not quite clear what you're asking.
More information would be helpful, including:
1. what software you want to use to play your song,
2. after a certain amount of time has passed
since what has occurred? (i.e since VC has loaded, since you issued another command, since a light turned on, etc.)?
But basically, you can create a command that uses VC.EventTimer to trigger your other, play song command.
http://voxcommando.com/mediawiki/index.php?title=Actions#SetEventTimerHere, when I turn on my living room light it triggers the event timer command. In five minutes the timer goes off and triggers my existing MediaMonkey play song command, passing it the specific song, "Wake Up Little Susie" as the payload:
<?xml version="1.0" encoding="utf-16"?>
<commandGroup open="True" name="play song in 5 mins" enabled="True" prefix="" priority="0" requiredProcess="" description="">
<command id="1121" name="Play song in 5 minutes" enabled="true" alwaysOn="False" confirm="False" requiredConfidence="0" loop="False" loopDelay="0" loopMax="0" description="">
<action>
<cmdType>VC.SetEventTimer</cmdType>
<cmdString>5m&&playSong&&Wake Up Little Susie</cmdString>
<cmdRepeat>1</cmdRepeat>
</action>
<event>Vera1.Device.20.On</event>
</command>
<command id="113" name="Play Song {1}" enabled="true" alwaysOn="False" confirm="False" requiredConfidence="0" loop="False" loopDelay="0" loopMax="0" description="">
<action>
<cmdType>MM.LoadBySQL</cmdType>
<cmdString>SongTitle ='{1}'</cmdString>
<cmdRepeat>1</cmdRepeat>
</action>
<action>
<cmdType>OSD.ShowText</cmdType>
<cmdString>{lastresult}</cmdString>
<cmdRepeat>1</cmdRepeat>
</action>
<action>
<cmdType>MM.Play</cmdType>
<cmdString />
<cmdRepeat>1</cmdRepeat>
</action>
<action>
<cmdType>TTS.Speak</cmdType>
<cmdString>playing song, {1}</cmdString>
<cmdRepeat>1</cmdRepeat>
</action>
<phrase>Play</phrase>
<phrase optional="true">the</phrase>
<phrase>song, track</phrase>
<payloadFromXML phraseOnly="True" use2partPhrase="False" phraseConnector="by" Phrase2wildcard="anyone" optional="False">mmPayloads\mmSongs.xml</payloadFromXML>
<event>playSong</event>
</command>
</commandGroup>
The nature of the payload or whether you need one at all will depend on whether you want a specific song, what method you're using to play audio etc.