Dragon timer should always be up - for consistency
So, the buff timers we have are great. You get them if your team had vision of the monster's death, and not if you didn't (because it's "uncertain"). But unlike other mobs, it's ALWAYS certain when dragon is down.
This is of course because of the global sound, and how it shows up in the tab menu. You can argue that it's not "visual", but sound is an integral part of League. If you play with the sound off, you're not going to hear Sion ult, Rek'Sai ult, Janna's whirlwind, hitting an enemy out of view with a skillshot, etc.
So let's be consistent and stop those annoying chat timers for good. Make dragon timer up ALL the time.