We took the veeeerrry slowly approach with DD, who was potty trained day and night by 24 months I think (she's now 2.5).
I think we first got some potties at about 18 months as she seemed to be interested in wees and poos. We very very gently enouraged her to maybe sit on the potty before her bath, and just had it around in order to normalise it. We had absolutely no expectations (ie we weren't aiming to train her by a certain age).
DD has always seem me and DH go to the loo as she used to follow us about like a limpet!
Eventually she did some wees in the potty and we basically just encouraged that, and lengthened the time that she was without her nappy at home, until we were confident that she would manage a trip to the local playgroup without a nappy, gradually extending the outside trips we did with her in pants.
We never had a potette or anything and only did trips once we were fairly confident there wouldn't be any accidents. No cold turkey here either. No reward charts, chocolate button rewards, basically didn't make that big a deal of it. And actually we did have hardly any accidents.
Somehow she was dry at night about 2 weeks after being dry during the day.
This isn't a particular book's method btw, just what seemed to suit us and DD and was made up as we went along by me and DH, following DD's lead.
I have to say that she was the first out of her group of my antenatal friends' babies to be potty trained (by quite some months). Quite a few of them still aren't trained at 2.5. So I can either feel very smug about our amazing technique, or it might just be that DD is just the kind of child who took to it easily and we were very lucky, and DC2 (current in utero!) might be a whole nother ball game!
I think as long as you enter into it with no expectations, there can't be any harm in having a potty in the house and starting the process off.
Good luck
!