if (time >= 480 && time <720);
{
for (int i=0; i<=255; i++)
{
analogWrite(bluemin, i);
}
You don't need the for loop unless you want the output to ramp from 0 to 255 in less than a millisecond. If you want the output to be proportional to the time that has passed in the current period then use the difference between 480 and the time now to derive the PWM value for the current time.