Using an Engineering Recruiter and when to contact

My son graduates with his ME in May 2016. He has been looking for work doing the usual advice, contact companies to follow up, find alumni that may work at the company to contact, personalize his cover letters etc.

He applied to a job on Indeed that was posted by a recruiter. The recruiter, to his credit, emailed my son back the same day and said that the client is looking to hire right away so would not want to wait until June for someone to start. For some reason the job was posted by an IT recruiting company so it is unlikely they will have other ME related jobs to offer in future

So these are my questions:

  1. Are there Engineering recruiting companies that any of you who are experienced would recommend? I know Aerotek and Kelly seem to have a lot of ads posted.

  2. When should someone who is graduating in May contact an Engineering recruiter?

  3. What words of advice do you have if a new grad works with one? We live on the east coast and he is looking for work on the west coast.

thx