Yep. Submitted documents to agent at just after 5 pm on 14 July. Submitted additional docs (requested) via the agent at about 4:30 pm on 16 July and have been waiting ever since. Yesterday morning I asked the agent about the status (as I do not have access myself) and I was told it was in the "pre-approval" stage.
Submitted through an agent on 14 July at around 5 pm. Submitted additional docs requested to agent on 16 July late afternoon (around 4 pm). This morning I emailed the agent to ask about the status and she said it is still in the "pre-approval stage". I think it would have been better to do it without an agent because that way you can - at as I understand - check your status by yourself via the website whereas with an agent you have to wait for them to get back to you.
I believe you have to apply from where you are. I've seen posts here for Da Nang where people have used either HCMC or Hanoi. I'm in Hanoi now and submitted the application via and agent on 14 July at around 5 pm. On Wednesday (16 July) late afternoon they requested additional documents. I was told by the agent this morning that it is in the "pre-approval stage". But I've seen plenty of posts here indicating that Hanoi is as fast as 3 to 5 business days. Hope this helps.