How long should I wait to have loose skin removed after weight loss, and does OHIP cover any portion?

Congratulations on all your hard work at achieving such an
incredible weight loss. It is recommended that patients reach their ideal weight
and maintain it steadily for approximately 3 months before considering a
surgical procedure to contour the body. Any further weight loss or gain will
have an impact on the results you achieve following surgery.
In Ontario the only coverage available to remove excess
skin and fat is for the Panniculectomy. This procedure differs from the
abdominoplasty or tummy tuck because it is strictly for the removal of extra
fat and skin in the abdominal area. You will need to see your doctor to determine
if you are a candidate to for this procedure. Your doctor will refer you to a surgeon
who performs this surgery and an application to OHIP will be completed on your
behalf for review and approval.
Where the abdominoplasty differs, is that not only is the
fat and skin removed, the surgeon also tightens the muscles and takes special
care to contour the area for the best aesthetically pleasing results.
The panniculectomy procedure is typically performed by a
general surgeon. I encourage patients to meet with more than one surgeon to find
the right fit. If you are considering an abdominoplasty or other cosmetic
surgery, always meet with surgeons who are Board Certified Plastic Surgeons.
All the best,
 

There are no rules for after weigh loss.  After you start loosing your weigh normally the patient plateau and if there are less than 20 pound of close to reach the ideal weigh loss the plastic surgery can be perform and even if the patient looses some more weigh there is not going to be any effect in the result of the plastic surgery

As long as you're reasonably satisfied with your weight (and it is within a healthy weight range), body lift via excision-based techniques such as tummy tuck, arm lift, back lift, among others, can be a great option.

The general rule is to have your weight stable 6-12 months to ensure that you can really stick to a healthy lifestyle.  Take note that significant weight fluctuations can affect if not reverse the surgery's results. 

Also, the waiting period allows you to recover from malnutrition.  You may not be aware of this, but massive weight loss patients have some type of malnutrition (e.g., iron deficiency) due to the sudden change in their diet.  For this reason, surgeons typically work with their patients' bariatric doctor or primary care physician to eliminate or at least control potential risks. 

In terms of insurance coverage, most issuers will only pay the cost if you are able to demonstrate that the excess skin is causing non-healing irritation, skin breakdown, and back pain due to the heavy saggy abdominal skin.  Hence, you must present medical evidence showing that your surgery is beyond cosmetic improvement. 

Good luck and best wishes.