What’s the fastest way…

So, here's the situation:

I'm communicating between an Arduino Pro Mini 328 and Max/MSP on a Windows 10 PC over USB. My code is:

void setup()
{
  Serial.begin(230400);
}

void loop()
{
  char buf[48];
  sprintf(buf, "0 %d 1 %d 2 %d 3 %d 4 %d 5 %d 6 %d 7 %d", analogRead(0), analogRead(1), analogRead(2), analogRead(3), analogRead(4), analogRead(5), analogRead(6), analogRead(7));
  Serial.println(buf);
  delay(7);
}

How to only send a series of 8 10-bit values preceded by a control bit? And how to time it correctly?