Do you think that it is safe to swim in a pool six days before your period is due?

i only got them like 2-3 moths ago so i dont really want to use a tampon. i am going to a pool party with about four of my closest friends and only one of them don't no i have my periods. my last period was a week late so would that mean that my next one is likely to be late as well?
what do you think?
please help me!
thanks..