Sheldon:

Not arguing, But why do you think that?

Probably because the piercing will get caught/become irritated by your braces. Especially if you wear a labret stud in it, since it could actually get caught and pull, but even with a ring. You probably don't realize it because your mouth is used to it now, but braces are constantly cutting and scratching the insides of your mouth/lips. You don't want that constant irritation on a brand new piercing, it will just cause scarring.

 Wait until you get your braces off. 

Depending on the placement, the post could be rubbing against metal all day. I know that with how my lip piercings were positioned, they would have. And I did have braces too, so I'm not speaking without some experience.

*shudder* Makes me imagine having to hear nails on chalkboard all day.

Wait until you get your braces off. There are many reasons:

-The back of the labret stud could get caught in the wire of your braces and could possibly break one or two off.
-The inside of your mouth is constantly pissed off right now so it's very sensitive therefore getting the piercing would be more likely more painful than necessary and would cause excessive bleeding.  It would imo also swell more.
-Because of the constant tugging, the piercing would be harder to heal.
-Bacteria and food can get trapped in the small gaps in your braces which in worst cas scenario could even lead to infection
-http://wiki.bmezine.com/index.php/Electrogalvanism
-Your dentist would most likely kill you (Seriously though, some dentists (especially the ones that specialise in braces) might refuse to treat you if you have oral piercings and require you to take them out before they continue the treatment)
- With braces you likely have to have x-rays every couple of months to check progress. For that, you would need to take your jewelry out which could irritate a potentially healing piercing.

 I had braces for 2 years :)

Edit: the piercers I know actually refuse to do labret piercings on someone with braces, for all those reasons. 

Sheldon:

Nousagi, You had braces when you got your lip pierced?

No, I did not. I got my braces off two years before getting snakebites. But as far as memory serves, baed off position of both, the studs would always have ended up getting stuck and scraping against them.

 So a labret whilst having braces is a bad idea... but what about lowbrets?

 probably the best idea is to wait... I have braces... If fricken sucks when your checks or lips get caught! Imagine the added bonus of an open wound.. with possible infection

Pretty picture isn't it? :)

Don't, it will just piss you off.

Both myself and missus have had it.
For one, it gets caught under the wire when you talk so it's plain annoying.
It makes noise on your braces.
The position of the braces mean that (if wearing) a labret stud is forced underneath the wire, and so causing LOTS of gum errosion.

Just wait till there off, and it can be you reward.

 If you have braces, getting ANY oral piercing is a bad idea until they're off and you're done with retainers as well. Bacteria can build up much easier in your mouth with braces since your teeth are harder to clean, plus the issue of metal against metal and getting caught. Besides...braces can cost thousdands of dollars (been there, done that twice) and it's just not worth the pain and irritation. My piercer won't even do any oral piercings on someone with braces.