Ah, the "ticking time bomb" scenario. Ours was a 12-day strike that ended during a lovely dessert reception where Toddler in Chief's heart surgeon was giving a presentation. We spent nearly his entire speech in the restroom cleaning poop out of TIC's armpits and ankle-fat.
Fond memories aside, doesn't sound like LOD fought many potty battles since his kid was trained at 28 months. Don’t know if it was the cloth diapers, luck, or effective bargaining tools. If your kid doesn't show interest by three or (gasp) four, then be more proactive. You could be holding your child back. Many preschools don't take kids that aren't toilet-trained (no pull-ups allowed!), and your child could miss out on fun stuff, like Ikea kids-land where toilet-trained kids over 36" can climb and play (while parents shop child-free).
Danigirl wrote that early potty-training might not be "respecting your child's wishes and abilities." If we respected all of TIC's wishes, he would eat only ice cream, wear only PJs, and endlessly watch Blue's Clues reruns. As for abilities, I'd bet most three- and four-year-olds can tell when their body needs to eliminate waste. Sadly, disposable diaper manufacturers have convinced parents that it's normal to have big kids in diapers (it's good for business!). Does it come down to convenience? It is easier to let your kid dirty a diaper when you're at the zoo or Costco, a mile from the closest restroom.