you'd better off doing cardio first thing in the morning , even better on an empty stomach before breakfast ( if you can ) , it's very hard but that's the best & most effective way to burn fat .
when you make cardio , your body uses carbs as main source of fuel in the first 30 minutes then after the 30 first minutes your body starts to burn its fatty reserve . that's why cardio work out has to last at least 30 minutes if your goal is losing weight and has to be repeated constantly ( if possible every day to be effective ) .
of course your body will be craving for sugar and food after your work out but you have to be disciplined and avoid too much fat food & sugar .
don't starve yourself neither in the first days as the day you'll be reeating normally your body will jump on all the food you give it and will stock it as a prevention in case you starve it again in the future .
losing 15 lbs in 2 months is possible but requires discipline . key is regular cardio work out ( doesn't have to be heavy load , gentle cardio is also fine ) and balanced diet ( avoid fat , sugar , none total elimination but reasonable amount ) and you'll be fine in 2 months