All things being equal, you may have a bit more swelling and a tiny bit more discomfort with surgery while having your menstrual period, but this poses no increased risk or trouble for you or your surgeon. This is slightly more of an issue with breast surgery (more swelling and discomfort possible), but with tummy tucks this really does not seem to ever be an issue. So many women have irregular periods, or the stress and anxiety before surgery triggers an early menstrual flow, that rescheduling ends up creating MORE stress and overall trouble than it prevents!
Place a fresh tampon the morning of surgery, bring a spare or three with you to the surgery center, and notify the nurses caring for you. They are well-versed in helping you deal with this, and it poses no concern or risk. Let your surgeon know, and he or she will reassure you as well--we hear this all the time! Best wishes!