First, the egg hatches a minute after you set the clock.

Baby to child = 1 hour and 5 minutes
Child to teen = Varies. Japanese releases take 3 days, all others 1 day.
Teen to adult = 4 days.
Adult to marriage proposal = approx. 3 days.

Around ages 10-12, your Tama can evolve into Ojitchi or Otokitchi. If you're using an Entama or Uratama, you can get a secret character around that same time.
Time until death = Varies on the owner. Good health will keep it alive for a long time, while neglect can shorten the life span.

Pausing (available on non-Japanese versions only) pauses the growth of your Tamagotchi. For example. You have a baby for half an hour, then pause it for an hour. Babies take only an hour and 5 minutes to evolve, but as it's paused at 30 minutes of its life, it must wait until being unpaused to continue where it had left off.