For a month - you can. If you have a noticeable excess weight and you start, firstly, physical education, and secondly, you begin to eat in accordance with a well-thought-out diet, then just in the first month the results can be very clear, when the "lightest" kilograms-centimeters go away ... And in the future, the process will slow down.
In theory, yes. But it depends on exactly how much you want to lose, how you are going to do it, and whether you will keep this result, or lose weight by the date, and then let it go.
If you are going to quickly lose a large weight - either you will not succeed, or you will cause significant damage to health, or the weight will return as rapidly as you lost it. A relatively optimal rate of weight loss (this is very average!) - 500 grams - 1 kg per week. But in general, we would advise not to focus solely on weight - all the more, you say that it is the visual result that is important. Measure the volumes and focus primarily on them. Perhaps you have your favorite jeans, by which you can roughly understand what shape you are in.
In general, the main thing is to set yourself realistic deadlines and tasks. It is better to write down the deadline and the desired result for yourself somewhere. The streamlined formulations “to throw off by summer” work much worse. :)