If you decide to follow the two-days-on-one-day-off protocol, today is a rest day. If you'd rather keep going and perform tomorrow's workout, you can. However, it's essential that you get at least 2-3 days of rest per week.
Give your body a chance to recover. Otherwise, you'll find it tough to see results and even tougher to maintain the motivation. So unless you're really itching to train, take it easy and spend a little time stretching out your sore muscles. Then, get ready to hit your workout hard tomorrow!