When can I start using silicone gel strips on my TT scar and should I be placing anything in my belly button for shape? (Photo)

As an author of Scars and Scar Revision in Reoperative Plastic and Reconstructive Surgery, I am well versed in the potential treatment options.  Scarring is a produce of genetics. Some people are good scar formers, and others are poorer scar formers. No particular scar treatment is better than another. I advise that scars not be exposed to sunlight for the first year due to risk for hyperpigmentation. Silicone sheets, Mederma, and Biocorneum are reasonable and popular options. I recommend that the scar therapy begin after the scars have healed and there are no open areas, which usually takes 4 to 6 weeks.The belly button created should be done precisely.  Placing a marble is only necessary in patients who are poor scar formers and constrict the anatomy created.  Ask your plastic surgeon if this is even necessary.  
Kenneth Hughes, MD, ABPS Board Certified Plastic Surgeon
Los Angeles, CA

This is something you should discuss with your surgeon who knows you best. For my patients, I have them wait until their incision is completely healed before starting scar treatment. be sure to follow all post operative instructions. Good luck.

Dear Reliable1486,
every plastic surgeon has his own protocol to reduce scars. I recommend my patients to start using Biocorneum gel after week 6. I suggest you to discuss this with your plastic surgeon. 
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

Your surgeon is the best one to advise you on when it is okay to use scar treatments and belly button shapers. From the provided photo it does appear you are healing normally. Your belly button is still swollen but based on your other incisions it seems you are early in your recovery so this swelling is typical and expected.