Only kiss your boyfriend until you know that you guys are ready, which can range from as early as a week or two, to as long as a couple months. Be sure that you both are comfortable being around each other, and you know that giving him a kiss is only going to make the relationship better.
DO NOT just kiss "just for the heck of it"!
Most people wait until they see the following interactions with their boyfriend/girlfriend before they lean in for the kiss:

• He's held your hand before, and often
• He's put his arm around you (shoulder...waist...doesn't really matter)
• He gives you many, many, MANY hugs!!!! (trust me, a hug is the first step towards the long road to kissing)
• You're comfortable being yourself around him or her (which is a given, since you guys are in a relationship because you two can be yourselves with each other)
• And lastly......YOU GUYS ARE ALONE! (Trust me, it's always best to kiss your boyfriend or girlfriend when you two are alone. It's much more intimate, and having your first kiss with your boyfriend should not be done in a crowd! Kissing attracts a BUNCH of attention!)