After what time of working out we will feel improvement?
It depends. I'll assume you mean after how much days or weeks of working out will one start yielding results. There are several approaches; first you'd notice visible results about 3 weeks in if you do high intensity cardio exercises and lift heavy weights (which I will advise against if you're just starting off as a beginner, or coming back to exercising after a long time off) if you decide to take it slow, results will suffice in about say 6 weeks and this will also depend on your metabolism and your body's ability to burn off unwanted fat. At this time, people around you will be the ones noticing the changes on you. You'd hardly notice easily because it will be progressively slow until you look back at an old photo. Also know that working out to achieve physical result is only part of the much work that needs to be done for noticing improvements; the most important of all, are the type of foods you eat. Good luck.