Congratulation on your recent tummy tuck.I allow my patients do light cardio work-out after 4 weeks and full exercise (lifting/stretching) after 6 weeks after I have seen and cleared them.Each plastic surgeon has different post-op protocol/instruction. Please visit your plastic surgeon so that he/she can examine you in-person and give you the clearance.Best regards.
It is always best to ask your PS what they allow/recommend as we all do things a little different. I tell my patients they can start working out again at 4 weeks, but to take it slow. stretching is difficult in the core region as things feel tight for months. Don't over do anything. If it hurts then stop.