labelling the relationship..

When did you label the relationship or when did it become official!?  
I have been dating this guy for about 4 months and known him for like 4 years prior. He did recently (8 months ago) leave his ex of 3.5 years. I just wanted to know when would I call him my boyfriend ? Clearly we aren't friends, we kiss, have sex and hang out 24/7. We haven't really spoken about calling each other boyfriend and girlfriend.. I understand he may be still recovering from his ex, I just am a little confused