Personally I think going for slightly above maintenance calories while emphasising strength workouts is the best option. Consistency will do you the most good so find a program you can be confident at sticking to . I personally used the recommended routine from r/bodyweightfitness and got pretty good results, and I’m still working on it. It’s great because it’s very scalable by ability level.
A month isnt a lot of time so try not to be too heartbroken if you don’t have a massive body transformation, but you can definitely make a great start.
Go easy and build up slowly.
If joint pain stop immediately, and let that joint rest for one week or more.
A single rep into joint pain can often mean months out of the gym.
Shoulder is riskiest, followed by wrist, knee and hip.