Finally, if you DID bring it up, he would probably laugh because he already thought of you as his girlfriend already.
This is not to say that it’s “wrong” to commit to someone before 4 weeks; merely that you’ll have a better sense of who you’re committing if you vet him first, instead of giving him a free pass to boyfriend-hood because you like him and want to sleep with him.
To the original poster’s point, you really shouldn’t have to “bring up” whether he’s your boyfriend.
Just wait to see if he’s acting like a boyfriend FIRST; don’t treat him like one until he’s earned it. Practice sexclusivity (particularly if you can’t handle no-strings-attached sex) I’ve written about this extensively, so I won’t rehash the entire argument.
But, in short, if you are the type of woman who does not like the feeling of sleeping with a man when you have no idea whether he’s your boyfriend, STOP sleeping with men who are not your boyfriend.
I am very happy (and he said that he is happy when he is with me) and like him the more I get to know him.