You should be in good shape for this destination. I trained for 6 months by exercising, hiking 8 to 12 miles every other day, then hiking 4-6 miles each day for the last month before while carrying my full backpack. I also changed my diet and drank a lot of water. You will need to drink a lot of water in order to complete the climb. Even though I prepared myself the trek was more strenuous than I had expected. Many times I really needed to regain my focus and muscle my way through. It will all be worth it in the end when you reach Uhuru peak and look out across the beautiful vista. I long to return again. Remember that each pound of weight on your body must be carried to the top so try and lose as much weight as possible but still remain strong. Best of luck!

When are you planning to go? I would recommend at least a 3mo window (and ideally 6mo) to prepare. The longer the training period, the greater your likelihood of success.
On the surface, your weight should not be an issue unless it inhibits your cardiovascular strength and endurance. The 2 greatest challenges of Kili are altitude and distance, the climb itself is not particularly difficult and not at all technical.

To prepare I would recommend starting in the gym, walking on the treadmill. A slow, steady pace is fine. To test yourself and increase strength/endurance, carry a pack;l add weights to the pack as you get stronger. To increase the difficulty/simulate the climbing experience, raise the treadmill, but maintain the same speed.

Most of your training can be done in the gym. Talk to a trainer about weights to train specific muscle groups (and help you achieve your weight loss goals).

Weather (and location) permitting, then try to get out to nature. Find some trail hikes, ideally with varied topography (the higher elevation the better). Have fun, but be careful.

Then, when you’re ready to go, make sure you’ve got a great guide.

Good luck—Jambo!