hi emma, spoke to my boss today, he said that to go on the combined pill you would need to have completely weaned your child off the breast ( if still bf can use the mini pill though) no need to wait for af at all, just start on the first active pill and progress from there.
hope this has helped.
xxx
p.s
he also said that if you have any worries or concerns, speak to your doctor or local pharmacist, they should be happy to explain it for you.