Emma's almost 8 months and we just started a few weeks ago. I tried it with her when she was around 4 months, and all I did was sit her on the edge of the big potty. Stupid, I know..and she completely hated it. Then, more recently, my sister told me about sitting with her on the potty and also holding her over the sink, holding her under her thighs. That completely worked! I really relied on timing at first, and still do, for the most part. I knew that she poops first thing in the morning, if she's not too distracted by her big brother.
One thing I wanted to say was, don't force your baby to potty, but also don't give up right away. I know a lot of times, the last thing Emma wants to do is potty, because she's busy doing something else, but she would also hate a diaper change at that time, too, kwim? She really digs the books, too, to help her occupied. And I also agree that you should get a potty. I got her a Baby Bjorn little potty, someone remarked that it looks like a great dane water bowl. lol But it's a great fit for little heiny's.
And, it's super easy to clean out. I just rinse it out for the most part, and give it a good cleaning at the end of the day. The potty goes with us, wherever we go. Even in the kitchen. lol
She's to the point now where she thinks that going in her diaper is unnatural. Seriously, it's only taken her a few weeks to get really riled up if I don't understand she's trying to communicate her need to go. She fusses and arches her back, usually. Come to think of it, it's usually when she's nursing, so that probably triggers her need to eliminate. Heather's right, it takes time to learn what your baby is telling you, just like with every other need they have. But, with time, you'll be completely grooving with your child! It's great.
Btw, today was a mostly "miss" day. Emma's either nakie or we use a prefold with a snappi most of the time, so we did have a few spills to clean up. lol But, it doesn't bother me at all. She would clearly much rather go on the floor than go in what she's wearing, but in the car or at night, she will still use the diaper.
Good luck, and don't give up. Just have patience!