We weren't having that much sex for awhile. So we used condoms until I was 6 months PP. Then I was ok with getting pregnant again technically, though we were too tired to do it very much. Starting trying in earnest when baby was a year old. Worked within 6 months.
However, my cycle didn't come back until baby was 10 months old since I was breastfeeding. So for me, I think that would have been effective BC.
It also took us a long time to have #1 and #2 came much easier. I did not want to go on birth control so I didn't.