I managed a week, then shaved because of the itchiness.
Then I managed two weeks and shaved for the same reason.
Tomorrow is two weeks again and this time I've used beard oil after shaving and haven't really had any noticeable itch. Hoping to stick with it this time as I've never grown a beard in my life!
Thanks for the thread and advice guys! 
Aside from the obnoxious and unsolicited comments from others, those first few weeks is the worst thing about having a beard. I don't know if it is caused by the length being so short the stubble is rough and abrasive, the stubble holding more skin oils on the face, or the skin losing the exfoliation the razor was performing but that itchiness goes away when your skin adapts. It's like those first few weeks of shaving your head because my skin felt raw and damp until it adapted to being shaved.
