How long will it take for tummy tuck wound separation to heal? (photos)

20% is a very high percentage.  There are ways to get the risk well under 1%.  In either case, once the wound is there, it will need proper care to keep it clean and allow it to heal.  Expect it to take about 6 weeks.  You will know it is healing as the tissue becomes all pink throughout, which it will with dressing changes and a little wound care.  Then it will gradually fill in and close.  The scar may or may not require a revision once it is completely healed.   Good luck.  

Thank you for your pictures.  The percentage of in healthy individuals in my opinion and in my practice is definitely less than 20%. It's probably less than 5%. Sounds like a surgeon is doing all the right things. You can tell if it's healing when the measurements continue to get smaller.

Sorry for the wound necrosis. Most case in the amount of necrosis takes a few months to heal completely...You should be seeing 3-d shrinkage of the deformity.  

It is hard to tell from the photo you provided, but I would say that a few weeks of debridement and wound care and then maybe you can either have a secondary closure procedure or it will take time to heal secondarily which would be about 4-6 weeks by the size of the wound.