I think I'm going to book AwesomePup in for castration over the summer holiday too. He'll be about 18 months by then which is pretty much fully grown for a lab (although I think his brain will still take a few more months to catch up to the fact he's supposed to be an adult).
AwesomePup was a complete knob yesterday morning when he was off lead. He ran over to a female dog on the other side of the field (rather a long way from me, so it took me a bit to get over there to catch him), and he wouldn't leave her alone at all. He wouldn't recall, he ignored her be clear "go away" signals, etc. Her owner was (quite rightly) annoyed with him and with me. It was humiliating. He's back on his long training lead until we get his recall around other dogs back. He had been doing so well recently, I thought we'd sorted it, but not yesterday. We still need to work on loose lead walking as well, which was another thing that was doing ok until this past week.