Every Wednesday I write my state legislature, governor, and congressmen. I usually use the same email, sometimes I tailor it for shit that's going on at the time. For instance lately I've used hemp production increases tax revenue, and helping farmers, helping the economy. I live in the midwest, so helping farmers is a big thing.
Why do I write it on Wed?
If I write it on Sat, or Sun it won't be read until Monday, when there are several other emails I imagine. Your's is likely to get overlooked, and ignored.
Thursday - Friday there's a chance it will be read on Friday, but not get much attention and forgot about by Monday. People pretend to work on Friday, they don't really do much though, it's a lazy day.
So I send it Wed night, on my lunch break. It should get read Thursday morning.
I do believe calling, and writing works. Maybe not all of the time, but it's the easiest way to make your voice heard. Your congressman hires people to read his emails, and let him know what the people are saying.
Enough people get involved, the more the congressman hears "well sir, the people want . . . well they want weed sir."
norml.org, and mpp.org are awesome places to start. They list governors, and congressmans numbers and emails.