I think you wait until she is shortening her nights. So last night was 12 hrs, probably enough to carry her through another day. But as the wake ups creep earlier, so 11.75, then 11.5 then 11 and backwards, you will likely need to offer a nap on those days.
I'm sure those other people just had seriously tired and cranky kids and lived with it. They didn't know there was a gentler, kinder way to do it. Or they have kids that don't have tricky sleep needs.
Case in point, I was out recently with a kid just turned 3 and kid's parents. We'll call him G. So G and F and all of us went to a large park/playground. G was melting down and losing his mind on no nap because he hadn't napped for a few days. Turns out they had been letting him nap and then he wouldn't go to sleep until 10 at night and then sleep until 7 only. He was getting seriously OT. But they thought that just not letting him nap was the solution. So we walked home with a screaming 3yo and F just happily in his stroller (F didn't have a nap that day either, his was in the car on the way home). So yeah, I think sometimes these 'other people' aren't always telling the truth or they really just don't know what else to do.