You receive it exactly after 4 days the website updates. Unfortunately, you have to wait for the mail. You can’t call and ask. I tried but they would only send an email if you don’t get it by 30 days. 😐
I got the RFE for intent to marry back on April 4th and submitted by April 15. Haven’t heard back since then while I’ve seen people who submitted by May get approved already. It’s highly random. 😕