I Am Now X3 Weeks Post Operative After Having A

I am now x3 weeks post operative after having a sigmoid colectomy via laporotomy with anastimosis due to preforation of the bowel, I wish to know when it would be safe for me to commence light abdominal and core exercises........i can walk about 200yds x 2 times daily and my range of movement is increasing daily without any major pain. can you please advise??