There are still some disagreements re: chargen rules and hitting magic 0. Some would even argue that hitting magic 0 burns you out (even though that this is clearly not the case in crb, it is the case for technomancers in crb. instead of ruling as is, or more broadly to have technomancer rules work more like magic user rules, some would say that the magic rules are the incorrect ones and have them work more like the technomancer rules. Given the consensus that the technomancer rules are of much poorer quality and depth than the magic rules, I tend to favor keeping the magic rules in place and using them as a guide for techno rules.)
I don't play that magic score goes negative during chargen, especially for priority and sum to ten. There are no negative stats. If you start off as an aspected sorcerer priority d. And take 3 essence of 'ware. Your magic hits 0, your max magic drops to 3, and you can spend your meta special points to raise magic up or edge. Alternatively, you could use karma to buy back Magic during the last phase of chargen process, but of course your cannot say spend 15 karma to get Magic back to 2 and use a special point to get to 3.
Karma buy may be a different story, but it may be edition carryover bias. Let's say you pick up aspected magician for 15 karma and the free Magic 1. Some would say that if you got two essence worth of 'ware on chargen, you would have to pay the karma to raise that Magic to 3 to let it drop back down to 1, because there aren't the same kinds of steps in karma buy, it just kind of happens all at once. However, doing the math, this actually makes produces karmicly worse off characters than in the other two chargen systems. Karmicly similar characters can be created if that 15 karma and free Magic 1 is a floor. So let's say your aspected magician gets 2 essence worth of 'ware, their Magic would still be 1 without paying more karma and their max magic would be 4. If you want to raise Magic higher, you would pay the regular karma.