Senate
At the beginning of each new session of Parliament, according to Rules 12-1, 12-2(1)(a), 12-2(2), the Committee of Selection is formed to nominate a Speaker pro tempore[6] and to name senators to serve on committees. The Committee of Selection must report within five sitting days regarding the nomination of the Speaker pro tempore, and as the committee generally reports on both matters on the same day, committee membership is usually set within the first week of a new session. These committee reports are generally adopted the same day that they are presented.
To learn more please visit The Senate of Canada website.

House of Commons
Standing Order 104(1) provides that the Standing Committee on Procedure and House Affairs is charged to prepare and report to the House the lists of Members to compose the standing and standing joint committees. Once the report on the membership of the standing committees has been approved by the House, a meeting of each standing committee is convened within 10 sitting days by the Clerk of the House, for the principal purpose of electing a Chair.
To learn more please visit The House of Commons Procedure and Practice website.