Thank you for the question. Generally speaking, it is always best to achieve long-term stable weight prior to proceeding with body contouring surgery. Doing so, will increase the safety of the operation, will likely improve the outcome of the operation, and will decrease chances that additional surgery will become necessary subsequently. In my practice, I do not ask specific patients to achieve a specific weight prior to proceeding with tummy tuck surgery. I simply ask patients to achieve a long-term stable weight where he/she feels comfortable and does not expect significant fluctuation postoperatively. As you know, recruiting other professionals such as personal trainers, nutritionists, physicians who specialize in weight loss concerns etc. may be helpful to you. Seeking consultation with well experienced board-certified plastic surgeons will be your next/best step.
I hope this, and the attached link (dedicated to mommy makeover surgery concerns) helps. Best wishes.