I'll add my voice to the chorus that likes default char-gen. I like karmagen (the German errata version, where Attributes cost x5 and you pay the metatype cost in karma). But I would say you should either use build points or karmagen - the two character creation systems are not close enough to be interchangeable.
Now - I consider that the default level, for runners that are starting out (note that "starting" runners are not first-level characters; first-level was when you were working your way up to becoming a runner). Potentially powerful, but not prime runner level yet.
For a high-powered campaign, I would go with 500 BP or 1,000 Karma, with no Availability limits, although I would still cap gear at rating, say, 8 or so, 20 more points you can spend on resources, and up to two levels of initiation.
For a low-powered campaign, I would go with 320 BP or 600 Karma, with lower Availability (8 or 9), lower starting skill levels by 1 (one 5 or two 4's, skill groups at 3), and limit both starting cash and Magic/Resonance rating by half (125,000 Nuyen, rating: 3).
One note: The characters should be able to hang with each other, but it is an open build system - they will all have strengths and flaws, but they will NOT be comparable, power-wise. With specialists vs. generalists, and adding awakening and augmentation to the mix, PCs will range all up and down the scale. Worry more about how they mesh together, and be sure to give them each some "spotlight time", and you'll be fine.