We have a girl coming up 4 (Jan) and a boy coming up 18 months.
The girl was actually pretty smooth overall.
In saying all this, we tried training our daughter at about 18 months (we were both first time parents as well - and friends of ours had an 18 month old who was out of nappies) before our boy was anywhere near being around and she was clueless. You'd ask her if she'd done anything in her nappy and she'd look up at you and say "no" when it was obvious she had. We realised it was a bit futile at that early point.
At about 2 - 2.5 we decided she was pretty much ready. When we had pprox 50 nappies left in the carton we'd say to her 'we want you to stop wearing nappies by the end of this carton'. Then we started counting down each time we put a nappy on her.
We also started encouraging her to go to the toilet (she wasn't interested in the potty) every time she did something in her nappy, and kept referring it back to the nappies left in the nappy carton.
However, in the midst of that, our little boy arrived and of course she regressed a bit. So the process was a bit slower. Then one day, it just clicked with her and she decided it wasn't grown up enough to wear nappies.
She's still wearing nappies to bed, however mostly they are dry nowadays. She's progressing out to not wearing nappies to bed, however we're just being cautious.
I really felt like she was feeling a bit left out at child care when all her friends were going to the loo by themselves. That no doubt spurred her on.
I think you'll note when she's ready and at that point they need a bit of a push along. 22 months isn't ridiculously early, but if she's not showing any signs of wanting to get out of nappies, I'd ease into it.
So in summary
Positive reinforcement
Use some sort of mechanism to count down to something special - the birthday of your girl WHUFC?
Ultimately, they'll do it when they're ready - with a bit of coaxing and co-ordination from the parents
Best of luck!
Gadj