For document availability by date and by source, see this chart.
Committee hearings can be one of the most elusive Congressional documents to locate. The time between the event and its publication can be months or even years. Before the hearing is officially printed, you may be able to obtain hearing materials from the committee itself.
Sources for hearings are listed below. See also the Chart - Sources for Legislative Documents.
Microfiche - the library also has the official text of hearings in microfiche, from 1833 to 2016.