Prepregnancy VS postpartum cycles

What was your cycle length prepregnancy and now postpartum? (Especially at first)? My cycles were usually 26 days (28 max, but not likely) and now I think I had my first postpartum period last month (it was just brown spotting for 3 days) and I should be due today if they are regular again but no sign of it yet. What were your experiences? Did it go back to regular instantly?