First off, you don't know my wife. Any setup, loading, configuring, etc.. is annoying to her. Second, it took my Apple Watch from about 5pm one evening until about 11am the next day just to do the WatchOS2 update. That would kind of take the fun out of the watch. The second one I got took several hours, which was a lot better, but again takes a bit of the fun away.
All I was suggesting was that you paired it so that you could do the OS update ahead of time, and then left it at that state... no apps loaded or anything, just ready to go. Then she can start playing out of the box but nothing has been configured.
And as has been pointed out, if her phone is updated, the Apple Watch app will already be on the phone.
My wife would appreciate this pre-loading for sure, but everyone is different. Caligurl, the fact that you are on MacRumors forum puts you in a whole different category from my wife. She doesn't use social media like Facebook, she has no idea what a forum is, and when anything on her iPhone or iPad doesn't work perfectly, she calls me and complains. Any updates that are done are when I tell her I need her devices for a while, and same for backing up her stuff, except when she fills one of them up with photos/videos and I get the call that she can't take any pictures. An emergency backup of photos is then done, followed by forcing her to sit and delete anything she wants to get rid of on the phone.
Not sure if the OP's significant other is like my wife or not, but if she is then I'd seriously consider a pre-config to make the experience fun for her instead of a "oh, we've got to wait several hours while it loads and updates".