Hels, I completely changed shape after having James so I'm gonna have to really work at toning up this time!! Swimming and aqua aerobics did the trick for me.
Mel, do it when you're ready. J was about 4 months when I started and it took me 6 months, as Ang says 9 months on, 9 months off. This time I am SO ready now that I've got to go for it while I'm motivated. I'm not doing more exercise above the usual walking around I do with the pushchair, and won't until I hit a WW plateau.
Look after yourself and Flissy first and foremost
Lo x