Yes you may. I would suggest going abroad by the time CIC receives the application. As soon as they start processing it, which will appear on ECAS as in process, i'll stay put in Canada up until the Oath. A 1 month vacation from the time CIC receives and opens your mailed application will be enough IMO. As soon as your back, then you'll just sit back, wait for progress on your application. This is based on our experience.Good luck.