Android Wear has a dedicated timer app that was added in a semi-recent update, but it’s pretty lacking in features. MoveUp! MultiTimer, on the other hand, has all the features you could ever want in a timer app for your watch. You can have multiple simultaneous timers, timer names, custom colors, vibration patterns, and more. There’s a $1.99 pro version upgrade that adds unlimited timers. It looks like the free version is limited to four, which is still plenty for most people.
MoveUp! MultiTimer (free, $1.99 in-app upgrade)