RFE response time?

[confessions]

My H1B transfer petition filed in premium processing on 6/9 got an RFE on 6/16 for unavailability of client letter. As of today 6/26, yet my employer/attorney have not responded to it.

Can some one share their experience/knowledge on how long usually does it take to collect the required evidence and send the response?

[inadmissible]

The RFE letter will state their expected timeline, by which they will consider the application abandoned. Usually 30 days. Refer to the RFE letter for specific guidance.