I'm curious to know what everybodys oppinion is on exchanging there queen with there opponents queen. When is an ideal time, if there is one? I know this is hard to answer, depending on the game and the individual playing, but when do you feel comfortable in doing so? Earlier the better or later in the game? Up on material or doesn't matter? I myself am not sure, but would say that I prefer to be up on material during the middle or end game.

A general principle is to trade queens when you are up material and to avoid the queen trade when you are down material.

 

Personally for me I prefer to trade queens early if possible because I feel I am a better endgame player rather than tactical player which provides me with better chances.

We all want to be superior materially especially at the middlegame and better in the end game.  Making all things equal, when material is equal, I'm inclined to offer a draw.  I want to exchange queens when I'm superior in material and position, which is apparent in the end game and middlegame.  If the opponent's queen is playable (not trapped in a corner, etc.), it'll be hard to force checkmate, and there's a great danger of draw via perpetual check especially when the king is not guarded (when you're attacking, e.g.).  Because of this, while you like to remove the queens, your opponent might resist your move.  The queen is a great asset for your opponent--so... try to remove them from the board... 

Trade if you want to simplify the position, magnify a material advantage, or force a recapture that leads to positional or tactical gain.

Wiseman say " Exchange queen if in your advantage to do so, or if in your disadvantage not to do so"

It is also good to exchange any piece (not just Queens) when you will gain tempo or an ideal position on the board.

I Instruct My Younger And More Inexperienced Scholastic Players...And For A While Even My Own Kids...Exchange Queens When You Can Because Trading Your Queen Is Better Than Losing Your Queen...And Also As A General Rule...Make Even Trades When You Are Up In Material...

http://www.chess.com/article/view/dont-fall-in-love-with-your-queen

I've heard to trade queens if you can. This will happen early (in my experience). Doing this will often find your opponent in a position where he takes back with his king, thereby losing his chance to castle...which is rather valuable if you think about it.