Whatever you do follow the care instructions that Brooks provides, not some internet cycling dead guru, or some friend, etc. Brooks has been making saddles for over 100 years and they know how to treat the saddle to make it last a long time.

Adjusting the saddle according to Brooks should be about a 1/4 a turn every 6 months, which I do think is a bit much but it also depends on rider weight. I found that the first year of either of my B17 or the Swift that I needed to make a 1/8th turn adjustment, after that the b17 required only one other adjustment about 6 or 7 years later, the Swift about 3 or 4 years later. You can tell how much to adjust it by, simply check the bolt's snugness before installing it when it was new to get a feel for it, then check it after the first 6 months then again at a year, then simply check it once a year and snug it like it was when new. If you never adjust it like Sheldon said the saddle will slowly turn into a hammock, you don't want that.

Brooks will survive rain but I try never to expose a leather saddle to rain. If it does get wet never adjust the spanner when the saddle is even remotely damp. I do use the Proofide once a year and apply it like you would with shoe wax and polish it in. Then afterwards I apply KIWI neutral colored (don't get colored wax or it will stain your shorts) paste wax (liquid or cream will not work as well), and rub it in and polish. but on my touring bike with the b17 I carry a saddle cover just in case, on my road bike with the Swift I don't and it has gotten wet with no ill effects.