A tummy tuck, if not "mickey moused" is a big procedure, one of the biggest cosmetic procedure we routinely do as plastic surgeons.
To combine that with a C-section and childbirth, by themselves very significant physiologic events, invites problems. Imagine the mother had a blood clot , a significant risk with pregnancy and C-section, and died... because they had a tummy tuck at the same time! Or the patient had a suboptimal "quickie" tummy tuck because the surgeon was nervous about the patient already being compromised from childbirth.
Structurally, the tissues after childbirth are very soft. They eventually shrink back and become firm again, and hold sutures much better after 6 months.
So I would avoid the temptation, the risk... and the substandard results.
