Instead of moving the file afterwards, you can tell mirc to save it to the right folder. The DCC Get Folders feature is designed exactly for this purpose: Alt+O -> DCC -> Folders

If you want greater control over where each file goes (eg send only certain files from certain people somewhere), you can use the CTCP event and /dcc get:
Code:
ctcp *:dcc send:?:{
  if *summer*.jpg iswm $3 && $nick == YourFriend { dcc get c:\pic\summer }
}


/.timerQ 1 0 echo /.timerQ 1 0 $timer(Q).com