I can't comment on Aero's, but I studied with BGS and they were brilliant. If you're studying with BGS and you can put in the hours, there's nothing stopping you completing it quicker than a traditional full time course in a class room. It just depends on how quickly you can get through the material. Just bear in mind you have to attend a week-long revision week at the end of each module of which there are three. This can be done in person of via webinar. I've heard of some people doing the whole lot in three months, but this really would be quite some undertaking in my opinion. Also, with BGS you could start in a few days time if you really wanted! You'd just buy the materials and crack on!
However, unless there's a specific reason to shoot through it as quickly as you can, there is no rush. I'd say the majority of people I saw taking exams were in their 30's and at 24 you have many years ahead of you. In my opinion, it's far better you take your time and make sure you understand the material properly. This is another thing I specifically liked about BGS. They had pre-recorded webinars covering the meat of most of the topics which helped with revision or even taking the edge off stuff that was difficult to digest as written material. The handy thing about this is you can also easily rewind and re-watch the bits you didn't quite understand the first time around.
I believe Pad Pilot is a different application; BGS have their own which can run on a variety of platforms.
I hope that helps and good luck
