Loop between a date of every month,

[330R]

bool  stuffDone = false;
int dayOfMonth;

if (dayOfMonth == 4 && !stuffDone)
{
  // do stuff here
  // will only run once, because at the end...
  stuffDone = true;
}

if (dayOfMonth != 4)
{
  // the next day, we reset it
  stuffDone = false;
}