My 3yo son knows what guns are and to not touch them. He sees me with a gun everyday, so it doesn't phase him a bit to be around them or see them.

I even experimented with him one day and left an empty gun on the bed, since I know he likes to play on it. He was never out of my sight for one second although he didn't know that. I let him climb on the bed and as soon as he saw the gun he jumped off the bed and came to find me to let me know that I had left a gun out. I had him take me to it and he stood at the foot of the bed while I retrieved it. Once he knew it was there he wouldn't go near it. If he keeps up like that I may wind up taking him to the range at an earlier age than I had planned.

BTW, congrats on the young'un. If this is your first, it won't be long until you can't imagine not having him around. Before you know it you will have two of them running around.