Man, that's a pisser! I've been pretty lucky with liquid yeast so far. I guess the optimal strategy would be
1. Make an appropriate starter so that it's ready the day before you brew
2. Check the gravity of that to make sure fermentation did occur and you have viable yeast
3. Brew
4. Aerate for a minute with O2, then pitch.
5. If, for some reason, you have no activity after 24 hours, aerate again and pitch a backup pack of hydrated dry yeast.
Like fakr, when I pitch the proper amount of yeast into properly aerated wort, I see activity within 12 hours.