Pre-T I shaved the peach fuzz off daily. When I finally started growing something worth shaving, I still shaved daily. Then, to watch it grow in I shaved weekly. Now I've got a decent thing happening, though patchy, and I shave monthly. The last time I shaved was 2 weeks ago when my boss made a comment, hey, when are you going to shave? It's been two weeks and there is as much on my face now as it took a month before. Still patchy in areas.
One tip if you're patchy but can see light hairs in the sparse areas: just for men hair color. You only have to mix up a little (I use 1-2"), brush it on, I wait 20-30min (not the 5), then wash it off in the shower. Don't do this right before you have to go somewhere, as sometimes it stains the face and takes a bit to get it off. But it works. Has to be repeated, but still, it helps darken those pesky fuzz hairs.
Jay