回复：how long for the 2nd service request?

Don't worry. Calling for service request may not work. However there is a record in their computers that you have made a service request. You will be fine, saying will receive the approval notice soon. I have a friend who got a approval notice two weeks after current status without taking any action. Be patience.

After 45 days counting from May 17, you may call USCIS again using your confirmation number. But I think your case will be approved before that date. Good luck.