I just visited the INTERPOL office this past week. It's a headache to get in but their official hours are 8am to 4pm Monday - Friday. However, if you want to get seen, we were told by several employees there that they limit the number of people to 100 on many days. There seems to always be a line outside before opening so we got there at 6:50am and were glad we did since there were already 50 lined up. It may also be better to go there later in the week since we also heard from several others that Mondays were busy.
Best of luck!