I haven't told the boy yet, but I'm kinda leaving TLM's potty training until Christmas. By then, her daycare will be closed for 2 weeks and we can hang around sitting her on the potty every hour. We already ask her to sit on the potty at least once a day, just before bathtime, and if she manages to do something in it then we do lots of yelling and hooraying. I'm still not convinced, though, that TLM actually realises when she's poo-ed or wee-ed, until we show her the stuff.
But another, less pleasant milestone is threatening to cross the finish line before potty-training does - then giving up of daytime naps. She's missed her naps a few times in the last few weeks, though each time she's been a total ratbag all afternoon. Normally, if she keeps screaming, I'll get her out of the cot. But today, I let her scream for 15 minutes and she actually went all quiet after that (I'm assuming she went to sleep).
So I suppose crying it out must apply even to near-preschool age.