I applaud you for the caring thought. To answer your question, I believe you can link the watch to his phone and then shut off the watch and there shouldn't be any notifications come up on his phone. Notifications come from the phone...and go to the watch.
I really love the thought behind this, but I wouldn't suggest it. Part of the enjoyment of the watch, is the whole process of opening the package, turning it on for the first time and learning how the watch connects to the phone and the process of how it all works together.
Please take a couple moments and register on the site, so you can follow this thread better, and please post back here after you give it to him.
Congrats on your engagement!