When do you think I ovulated? OHSS symptoms on cd17.

I was doing an IUI this cycle with 100 mg of clomid. I had a u/s on cd15 and it showed that I had 6 follicles. My RE said that we needed to sit this cycle out and that there could be a chance that I would develop OHSS. I started showing symptons of OHSS on cd 17. Do you think I ovulated on cd 16 or can you have the OHSS symptoms before ovulation.