So purely rental for time building? No flight training?
Every starry-eyed fATPL-student from Europe will need a BFR for their 61.75
Flight training under EASA is becoming nearly impossible, with protectionist rules from Europe, against EASA flight training done outside the EU. At start, I would go with rental only. Flight training is incidental to that business model, unless you get full-time students(which is unlikely).
Best way is to rent one plane for one student for one week, and expect them to fly 30 hours that week. Purely block rate, free use withing the CONUS, done.
Base the operation somewhere (Arizona maybe?) with endless sunshine and VFR days year around, and watch the money (slowly) flow in.
Cheap inital costs, low risk, and big potential when marketed correctly. So just about everything a jet charter isn't
From there, after a few planes, you can start a workshop mainly dealing with your own planes, then when word of mouth goes around because you are doing things better than anyone else(which is a requirement for ANY startup), you get more outside customers, then you hire another A&P, and so on and so on.