MSP430F6779A: Waiting time before start SD24_B

Tool/software:

1 I wonder how long should I waiting before start the SD24, what is recommend number? (my application has critical task to start detect precise signal after start SD24 immediately), On the datasheet specify tON SD24_B internal reference turnon time is 200us on page 62.

2. What happened, effect to SD24, if waiting time less than 200us or no waiting time?

3.On the TI example code why TI specify waiting  __delay_cycles(0x3600); , 13ms on clock 1Mhz, Could you explain why use this number?

msp430f677xA_sd24b_01.c

void main(void)
{
    WDTCTL = WDTPW | WDTHOLD;               // Stop WDT

    SD24BCTL0 = SD24REFS | SD24SSEL_1;      // Select internal REF
                                            // Select SMCLK as SD24_B clock source

    SD24BCCTL0 = SD24ALGN | SD24SCS_4;      // Left-aligned, group 0
    SD24BCCTL1 = SD24ALGN | SD24SCS_4;      // Left-aligned, group 0
    SD24BCCTL2 = SD24ALGN | SD24SCS_4;      // Left-aligned, group 0

    SD24BIE = SD24IE2;                      // Enable channel 2 interrupt

    __delay_cycles(0x3600);                 // Delay for 1.5V REF startup

    SD24BCTL1 |= SD24GRP0SC;                // Set bit to start conversion
    __bis_SR_register(LPM0_bits | GIE);     // Enter LPM0 w/ interrupts
}