Everyone is different, and I am afraid I am not qualified to give you advice, but I'll let you know what I did and you can decide if that may work for you.

I started out by cutting my calories pretty severely to drop most of the weight. That took a good 6 months, but most of a person's weightloss comes from diet - not exercise. My logic was that it would be easier for me to exercise when I had less weight straining my joints and back, which was true. Before I started, I had knee and hip pain which made doing cardio a real, literal pain. After I dropped the bulk of my weight, it was like magic, most of my joint pain disappeared.

So after 6 months, I started going to the gym, dropped my goal from 2 lbs per week to 1 lbs, and factored in the exercise for my daily tracking. This meant that I could loosen my eating restrictions which, mentally, was something I needed. (I can't give up stuff like cake, by God, so this means I can splurge on it now and then in a week without really setting myself back.) At the gym I started with simple cardio to dust of my muscles and circulation.

After a few months, I realized that I wanted to add in the weights to tone. So that was when I started. When you go into doing weights, you NEED to have a specific goal of what you want in mind since all the different weights build different muscles. I would highly encourage you to speak with one of the trainers at the gym at that point, or check out a fitness community to decide what kind of a circuit you want to do.

I'm not sure if you're a man or a woman, but each sex builds/stores muscles and fat in different ways/different rates. The guys at my gym tend to focus on things like heavy lifts, squatting, their abs. I wanted to tone my chest, arms, and thighs, so I spoke with a trainer and worked out a circuit of bicep curls/benching/leg presses while still doing at least a half an hour of cardio to keep my heart rate up.

Pshew. I know that was a lot of exposition, and I'm sorry.

TL;DR Maybe focus with losing the bulk of your weight first so that getting in shape is easier/less hard on your joints. But don't be afraid to get in there and exercise, too.