I agree with NinjaCyborg - that is less than ideal advice in that manual.
Of course it needs to happen before AddNetInterface, but put it at the top of your Network-Startup, that is where it belongs, and where it won't be overwritten.
In general, no local customizations should be made in the main Startup-Sequence nowadays.
Another benefit is that Network-Startup is executed asynchronously, so the rest of your Startup-Sequence is not delayed by waiting for your network stuff to succeed.
Best regards,
Niels
