Philosophically, you need to decide if borrowing is something you are comfortable with or not.
I think Magical Beginnings is GREAT for those who buy while at (or shortly after returning from) WDW. They've just gotten that trip under their belts and can probably wait a year before returning.
Others just have to make the same tough decision as you.
We only purchased 150 points, and I'm comfortable borrowing to the point that we will not have to worry about banking points. In other words, if we are planning a stay and have enough points for 3 nights with 10 pts left over, I have no qualms about borrowing a few points to make it a 4-night stay.
Of course we haven't been members all that long, so it's hard telling what extremes I might go to if a conference or work travel steers me toward Orlando for a couple of days unexpectedly.
Discuss the reality of the situation with your family and make a group decision. Continuously borrowing leaves you with less flexibility. If you were to have to cancel a trip, you cannot bank borrowed points. And you'll have nothing in reserve (so to speak) if an unexpected Disney opportunity may present itself.