League of Legends (LoL) Question: How do you keep track of cooldown timers that don't have a visible tracker

It can be game changing during the laning phase to use Taste of Blood or Hextech Revolver when available. The first offering sustain and the second giving enough damage to dictate when you should engage.

How do you personally keep track of these timers?

So far, I've found for Taste of Blood its best to leave open my rune page panel besides my skill bar. This way I can make note of the number i've healed so far from using the rune. When I see it increase I make note to wait what I presume to be around 20 seconds and when I attempt to proc it again I watch for the number's increase showing it was a successful proc. By doing this I'm optimizing my usage of the rune and increasing my sustain by quite a lot more.