Something that I didn't do originally is to trim the battery leads - comparing the photos, you can see how much excess there is. This makes re-assembling the watch easier as there is less excess wire to tuck away and find space for.

I also didn't get a photo of the battery just on its own, to show just how long the leads are, but they're about 3 or 4cm I'd say. In terms of the length I ended up trimming them to, it was approximately 1 length of the top of the battery (the yellow taped portion in the last photo).

If you haven't potentially having a look at the Reddit thread linked in the Introduction is a good idea, as it gives you context for just how tight these batteries are to install, and how important selecting the right battery is, as well as knowing what you're getting yourself into!