How to avoid ADC Interrupt overflow during initializa​tion/confi​guration?

I am using simulink for TMS320F28027 (at 40MHz clock freq). I have programmed ePWM for 450 cycles (on first event trigger) for ADC interrupt.

//
int main(void)
{
volatile boolean_T runModel = 1;
float modelBaseRate = 0.005;
float systemClock = 40;
c2000_flash_init();
init_board();
((void) 0);
SB_300W_CL5_Rev2_initialize();
configureTimer0(modelBaseRate, systemClock);
runModel =
  ((void*) 0) == (NULL);
enableTimer0Interrupt();
enable_interrupts();
globalInterruptEnable();
while (runModel) {
  runModel =
    ((void*) 0) == (NULL);
....
}

//
void enable_interrupts()
{
EALLOW;
PieVectTable.ADCINT1 = &ADCINT1_isr; /* Hook interrupt to the ISR*/
EDIS;
PieCtrlRegs.PIEIER1.bit.INTx1 = 1;   /* Enable interrupt ADCINT1*/
IER |= M_INT1;

/* Enable global Interrupts and higher priority real-time debug events:*/
EINT;                                /* Enable Global interrupt INTM*/
ERTM;                                /* Enable Global realtime interrupt DBGM*/
}

I have observed following things: 1. ADCINTFLG was set even before executing enable_interrupts() (as ePWM was initialized and configured earlier) 2. almost 425 cycles are spent between last instruction of enable_interrupts() and first instruction of globalInterruptEnable(). I don't understand the reason. 3. And,so, ADCINTOVF is set even before entering the infinite while loop.

Could you please let me know how to avoid interrupt overflow getting set?