I will be using aero crew solutions when my time comes. I have heard of ECC but was unfamiliar with Aero Crew. I talked to aero crew the other day and he was extremely helpful and answered all my questions with great expertise.
Do not wait until you have an interview at hand to do the prep. It's not a one and done process. You need time to digest the info, revisit it, talk with your coach, etc. You want to to take the first interview chance available, not say "oh sorry I need two weeks to prep." That time is now.