After my first, i took a nice, slow approach. Your body needs time to recover and adjust. Your body really does take a long time to recover - they say if it took 9 months to grow and change, it'll take just as long to adjust back again.
I had stretch marks but they faded.
I put on 3 stone. Started focusing on my diet at 3 months. Lost 1-2lbs a week. Started exercise at 6 months. Reached my happy health and weight at about 12 months.
Just had baby no.2 and this is my plan:
Now: Focus on building PFM and transverse abdominal muscles (deep abdominals)
2 months: Focus on more intense PFM and knee exercises (pregnancy fucks with my knees )
3 months: Walking, yoga and possibly barre
6 months: Weights and HIIT orientated home workouts
I have no idea what weight I am. I'm not worried like I was last time. There are some things that are different about your body that you get used to. My boobs will never look as full as they used to without a bra on. Sometimes you can see the stretch marks in a certain light but I'm quite proud of them. But on the whole your body goes back to how it was before. Just take it easy and don't pressure yourself. You've just grown a person.