That is exciting that you are going to a formal ball! Do you have a dress?
Do you have an exercise tube at home? That is the way to go. All you have to do is grab the tube and do one exercise for one minute, any time you have a free minute. You'll find at least 5 free minutes during the day, and it adds up fast. Look at FitLink's exercise tube workout for pictures: www.fitlink.com
Congratulations on the birth of your 3rd child! I am so excited for you!