It's taken me about 9m to a year both times to get back to the right clothes size.
With DS1 I went from 9st 2 to 8st 7 by the end of the nausea phase then up to 13 st in the remaining 5-6 months. Despite the initial loss, I gained bump rapidly and started buying maternity clothes from 8 weeks. Most maternity clothes were outgrown by the end of the second trimester. I think the rapid gain was mostly due to SPD settling in early and leaving me pretty much housebound at the end, so a loss of metabolism from moving, and water retention.
Second time the nausea was better so my weight was stable in the early months and I had the energy to keep moving until the SPD kicked in again. I then managed to keep moving on crutches (first time was undiagnosed despite trips to the drs). I kept the gain down to 12st. I think the main difference was water retention. I avoided carpal tunnel syndrome the second time.
DS1 kindly gave me saggy skin and a CS overhang. DS2 kindly trashed my pelvis and pelvic floor for several months. Both times I started my weight loss and exercise with staggering to the end of the road and back (then bed to recover). I concentrated on eating nutritious food, and fairly normal habits, and using the deficit from breastfeeding for loss. Also gradually rebuilding fitness and muscle.
It takes a while to slim back to my maternity jeans! I have an interim wardrobe until I reach my usual size.
I think much of the "me" weight late in pregnancy comes from the SPD reducing movement, and exhausting me with constant pain and disturbing my sleep encouraging a desire for quick energy carbs.
I've ended up slightly lighter after both children. I find it more effort to maintain these days, not helped my slightly separated abs. Alas my tiny bust doesn't hide the mum tum zone when it's having a bad day.