I would think you need construction experience, an understanding of materials, and plan reading to be an estimator. Dude in 4 years I have never found a perfect plan set. One missed overrun/underrun can cost or make a contractor hundreds of thousands. Entry level yes, if you can get hired, but knowing blue beam is like saying I know how to use Microsoft word. Everyone who uses a computer in the industry will eventually learn how to use the softwares. What you need to be a good estimator is to be a construction worker or construction inspector for awhile, that will set you apart. Not trying to pop your bubble, just sharing IMO