If you send a message to a senator when action on that issue is not going to happen for sometime, your message will be saved but shelved. You can only hope that when it is relevant it will be retrieved. Or put another way, somebody will remember that it was shelved and know how to find it.
This means you should keep track of what's going on in committees that are important to you, pay attention to communications you receive from associations to which you belong, visit committee websites, and follow activities of your senator in the newspaper, on TV, and through social media. All of these things will help you determine if action on an issue, that is near and dear to your heart, is eminent.
Developing a basic understandings of the Congressional calendar and the differing roles of Senate committees will also help.
In any year the first committees to take action are the Senate and House Budget Committees. The Senate and the House must complete their work and agree on a budget resolution by April 15. Budget committees with the help of the Congressional Budget Office review the president's budget proposal (released at the end of January or early February) for the next fiscal year (which begins on October 1), hold hearings, draft budget resolutions, vote on them, hold a conference to reach agreement on differences between the two versions, and then both vote on a final budget resolution.
This resolution does not go to the president. It is for use by the Congress, especially the appropriations committees. The final budget resolution sets targets on how much money should be appropriated for federal agencies, not specific programs within agencies. The budget resolution may also include recommendations related to changes in tax policy and changes in entitlement spending (such as programs covered under the Social Security Act -- Medicare, Medicaid, SSI, SSDI, and OASI).
There is no requirement that Congress must agree to a budget resolution. In fact, we did have resolutions in 2011 through 2013.
Individuals tend not to focus on budget resolutions. The leadership on the appropriations committees do. They want to know what the limits are on what they get to work with.
The next committee to swing into gear is the Appropriations Committee. There is one in the House and one in the Senate. Each has 12 subcommittees responsible for specific federal agencies. As a result, we have six real chances to influence what is ultimately appropriated for programs we care about -- one chance each at the subcommittee level in the Senate and the House, one chance each at the full committee level in the Senate and the House, and one chance each when an appropriations bill goes to the floor of the Senate and the House. The last chance is when House and Senate conferees are negotiating, trying to come up with the final version, they both would pass.
Appropriations subcommittees are powerful because they decide exactly how much money each federal program will receive come October 1. Ideally, the appropriations committees are to finish their work by May or June. However, appropriations work is seldom finished for all federal agencies by October 1. When all work is not finished the Senate and House put together omnibus appropriations bills that throw in all the unfinished appropriations work. All kinds of crazy things can happen then. Appropriations chairmen have tremendous power. The public seldom knows what the result is until it's a done deal.
The implication for you and me is that we should send our messages to key Senators early and often, so what we want in funding for programs makes it into bills, amendments to bills, and final versions of appropriations legislation whenever that happens. Provisions that get in early tend to stay in.
A third type of committee is an authorizing committee. By my count there are 13, although there are five additional committees in the Senate designated as special, select, or other (https://www.senate.gov/pagelayout/reference/e_one_section_no_teasers/org_chart.htm).
Authorizing committees are under no obligation to take action within a certain time frame. Their job is to create new programs that meet a need, continue established programs, most often with amendments, when they expire, and oversee how programs are doing. Many well known programs like the EPA (1978), No Child Left Behind Act (2007), and the Developmental Disabilities Assistance and Bill of Rights Act (2000) have expired and should be reauthorized. These programs are well known and in some quarters well-liked, so it is highly unlikely that a member of Congress would object to them receiving funding even though their authorizations have expired. Although, such a move could happen, if a Senator did not like a program. All the Senator would need to do is raise a point of order when the appropriation for the program, which has expired, comes up.
From a timing perspective, authorizing committees want to finish their legislative work before appropriations decisions about relevant programs have been made. So, although hearings and drafting of legislation related to authorizing committees' work could occur at any time, we tend to see these activities in the spring and early summer. Like most other committees, authorizing committees have subcommittees. We have multiple opportunities in both houses to influence legislation being considered at the subcommittee level, full committee level, on the floor, and during conference between the houses.
Now you have a snapshot about when to send your message and to whom. All things being equal, here's a a summary.
Send your message to the budget committees now saying how great the programs you care about are -- kind of a shout out.
Send your message to the appropriate appropriation subcommittees in March.
Send your message to authorizing committees as soon as you get a whiff of a hearing. Or, if you want to see some action that is not likely, write now and raise it.