I don't think it is ever too early! If you find a large cage in good shape, for a good price? Go for it!
The larger parrots have incredible beak strength. They can disassemble cheap welds in a matter of seconds. So make sure that whatever cage you purchase is well made. Size is so important (you know, get the biggest cage you can afford and that will fit through your front door), but construction is also important.
I always thought Galah cockatoos were gorgeous.