Wumi1234:
This Agents who assist others to get US visa interview appointments. Are they for real? And does it not have any effect on the visa application?
Please I need answers

It is a high risk but there have been genuine cases with visa success. If you must use, only engage by direct recommendation of someone who you know (know personally) and has been successful.

No you should not be worried. the rough estimate is 3 weeks and as long as Application received is noted on the CEAC website, that should be fine. I cannot speak to the delivery information but it will be definitely delivered to the address stated at the time of your IW appointment and you will be notified.

My advice - wait till a decision is taken (track via the ceac website), then you can follow up with DHL customer care if there are further delays. Take no action now