Pann has started humping things

he is not quite four months. isn't this a little early?! I haven't decided whether or not to have him neutered yet, my bf is very against it he says it's not right

but he's just thinking of himself and has sympathy pains already lol. But I'm just not sure. I want to know all the pros and cons so that I can make an educated decision. I'm just nervous because he's already humping things and he loves people children and adults and other animals, he's never been aggressive towards anything or anyone! I don't want that to change! Please help me make this decision, I love my baby and all information and oppinions would be extremily appreciated!